THE  DEVELOPMENT 


OF  THE 


PERIODIC  LAW 


F.  F.  VENABLE,  I’li.I).,  F.C.S., 


Professor  in  the  University  of  North  Carolina. 


EASTON,  PA.! 

CHEMICAL  PUBLISHING  CO. 


Copyright,  1896,  by  Edward  Hart. 


s~  7/,  2 
V ‘f  V 7 


TABLE  OF  CONTENTS. 


Prefatory  Sketch 


i-io 


CHAPTER  FIRST. 


PROUT’S  HYPOTHESIS  AND  THE  DOEBEREINER  TRIADS. 

§2.  The  Unity  of  Matter — §3.  Definition  of  Element — §4.  The 
Atomic  Weights — §5.  Remarks  of  Roscoe  on  Dalton’s  First 
Table  of  Atomic  Weights — §6.  The  Table  of  Thomson  and  Wol- 
laston— §7.  The  Table  of  Berzelius — §8.  The  Two  Directions  of 
the  Work — §9.  Prout’s  Hypothesis — §10.  Prout’s  Second  Paper 
— §11.  Berzelius  and  Gmelin  in  Connection  with  Prout’s  Hy- 
pothesis— §12.  The  Examination  of  the  Subject  by  Turner — §13. 
Penny’s  Results — §14.  Dumas’  Adhesion  to  Prout’s  Hypoth- 
esis— §15.  The  Extension  of  the  Hypothesis — §16.  Prout’s  La- 
test Views — §17.  The  Views  of  Meiuecke — §18.  Prout’s  Views 
as  to  the  Constitution  of  Matter — §19.  Early  Numerical  Rela- 
tions—§20.  The  Triads  of  Dobereiner — §21.  Dobereiner’s  Re- 
sume of  His  Law — §22.  The  Slow  Extension  of  these  Views  — 
§23.  Berzelius  on  such  Numerical  Relations 11-32 


§24.  Slow  Development  of  the  Triad — §25.  Dumas’  Address  be- 
fore the  British  Association — §26.  The  Effect  of  Dumas’  Ad- 
dress— §27.  Faraday’s  Views — §28.  The  Ascending  Series  of 
Kremers — §29.  The  Triads  of  Kremers — §30.  Gladstone’s  Ar- 
rangement in  the  Order  of  the  Atomic  Weights — §31.  The  Ho- 
mologous Series  of  Cooke — §32.  Kotikovsky  and  the  Com- 
pound Nature  of  the  Elements — §33.  Low’s  Theory  as  to  Com- 
position of  the  Elements — §34.  The  Extension  of  the  Triad  by 
Lennsen — §35.  Elaboration  of  the  Homologous  Series  by  Du- 


CHAPTER  SECOND. 

DUMAS  AND  THE  PERIOD  FROM  1850  TO  i860. 


IV 


table  of  contents. 


mas — §36.  Double  Parallelism  of  Dumas — §37.  Dumas’  Views 
as  to  the  Compound  Nature  of  the  Elements — §38.  The  Dumas- 
Despretz  Controversy — §39.  Pettenkofer’s  Group  Differences 
— §40.  Comparison  of  the  Elements  with  the  Compound  Radi- 
cals— §41.  Odling’s  Triads — §42.  Mercer’s  Comparison  with  the 
Organic  Radicals— §43.  The  Revision  of  the  Atomic  Weights 
by  Cannizzaro — §44.  Lea  uses  the  Atomic  Weight  Differences 
— §45.  The  Geometrical  Ratios — §46.  Other  Regularities — §47. 
Physical  or  Absolute  Atoms — §48.  Dumas  extends  the  Hypoth- 
esis of  Prout — §49.  Criticism  of  the  Work  of  Dumas — §50.  The 
Work  Accomplished 3 3-62 

CHAPTER  THIRD. 

THE  IMMEDIATE  FORERUNNERS  OF  THE  PERIODIC  LAW. 

§51.  The  New  Conditions— §52.  Stas’  Opposition  to  Prout’s  Hy- 
pothesis— §53.  Numerical  Relations — §54.  Parallelism  Revived 
— §55.  The  Pairing  of  the  Elements — §56.  Classification  by  the 
Atomicities — §57.  Relations  between  the  Atomic  Weights  and 
the  Densities — §58.  Brodie’s  Ideal  Chemistry — §59.  Brodie’s 
Conception  of  the  Genesis  of  the  Elements — §60.  The  Telluric 
Screw  of  de  Chancourtois — §61.  The  Work  of  Newlands — §62. 
The  Law  of  Octaves— §63.  Explanation  of  the  Existence  of  Tri- 
ads— §64.  Criticism  of  Newland’s  Law — §65.  Character  of  the 
Work  of  de  Chancourtois  and  Newlands — §66.  The  Remarks  of 
Crookes  upon  the  Priority  Claims — §67.  The  First  Table  of 
Lothar  Meyer — §68.  Hinrich’s  Deductions  from  the  Spectrum 
of  the  Elements — §69.  The  Pantogen  of  Hinrichs 63-90 

CHAPTER  FOURTH. 

THE  ANNOUNCEMENT  OF  THE  PERIODIC  LAW. 

1869-1871. 

§70.  Periodic  Law — §71.  Meudeleeff’s  First  Paper — §72.  Meude- 
leeff’s Horizontal  Table — §73.  Important  Features  of  the  Sys- 


TABLE  OP  CONTENTS. 


V 


tem — §74.  Mendeldeff’s  Claims  as  a Discoverer — §75.  The  Re- 
ception Accorded  the  Discovery — §76.  The  Evolution  of  Mey- 
er’s Table — §77.  Meyer’s  Table  of  1864 — §78.  Meyer’s  Table  of 
1868 — §79.  Meyer’s  Table  of  1870 — §80.  Mendeleeff’s  Tables  of 
1871 — §81.  Meyer’s  Later  Tables — §82.  Meyer’s  Curve  of  the 
Atomic  Volumes — §83.  The  Failure  to  Recognize  the  Import- 
ance of  the  Law — §84.  The  Criticism  of  Berthelot — §85.  Men- 
deleeff’s Reply — §86.  Ostwald’s  Criticism 91-117 


CHAPTER  FIFTH. 

DEVELOPMENT  OF  THE  SYSTEMS. 

1870-1880. 

§87.  A Return  to  Numerical  Regularities — §88.  Growth  in  the 
Belief  in  Unity  of  Matter — §89.  Baumhauer’s  Spiral  Arrange- 
ment— §90.  Additional  Work  of  Newlands — §91.  The  Synoptical 
Table  of  Gibbes — §92.  Wiik’s  Arrangement — §93.  The  Primal 
Element  of  Simmen — §94.  Wachter’s  Numerical  Regularities 
— §95.  Lockyer’s  Hypothesis  as  to  the  Compound  Nature  of  the 
Elements — §96.  Berthelot’s  Discussion  of  Lockyer’s  Hypothe- 
sis— §97.  Crookes’  Views  as  to  the  same — §98.  Zangerle’s  Nu- 
merical Relations — §99.  Lersch’s  Numerical  Relations — §100. 
Zangerle’s  Primal  Elements — §101.  Criticism  of  Meyer  and  Seu- 
bert — §102.  Meyer’s  Ideas  as  to  the  Elements — §103.  Groshans 
on  the  Nature  of  the  Elements — §104.  Other  Authors  during 
this  Period 1 19-149 


CHAPTER  SIXTH. 

THE  DEVELOPMENT  OF  THE  NATURAL  LAW. 

1880-1885. 

§105.  Revival  of  Prout’s  Hypothesis — §106.  Meyer  and  Seubert’s 
Review  of  Dumas’s  Work — §107.  Mallet’s  Views  Regarding 
the  Hypothesis  of  Prout — §108.  The  Views  of  Clarke — §109. 


VI 


table  of  contents. 


Crookes’  Views  as  to  this  Hypothesis — §i  io.  Meyer  and  Seubert 
on  Prout’s  Hypothesis — §m.  Groshans  on  Prout’s  Hypothesis 
— §H2.  Bayley’s  Attempt  at  Showing  the  Connection  between 
the  Atomic  Weights  and  the  other  Properties  of  the  Elements 
— §113.  Gladstone’s  Address  before  the  British  Association — 
§114.  Hartley  on  Spectroscopic  Evidence  as  to  the  Nature  of 
the  Elements — §115.  Hartley’s  Criticism  of  Lockyer — §116.  Nu- 
merical Relations  of  Fedaroff — §117.  Laurie  on  the  Physical 
Properties — §118.  Gerber’s  Modification  of  the  Hypothesis  of 
Prout — §119.  Mills’  Equation  for  Calculating  the  Atomic 
Weights — §120.  Carnelley’s  Study  of  the  Relations  of  the  Phys- 
ical Properties — §121.  The  New  Law  of  Groshans— §122.  Pe- 
lopidas  Compares  the  Elements  with  the  Organic  Radicals — 
§123.  The  Spiral  of  v.  Huth — §124.  Berthelot’s  Theory  as  to 
Primal  Matter — §125.  Carnelley  on  the  Periodic  Law  and  the 
Occurrence  of  the  Elements — §126.  Carnelley  on  the  Cause  of 
the  Periodic  Law — §127.  Spring’s  Diagram 151-179 


CHAPTER  SEVENTH. 

THE  DEVELOPMENT  OF  THE  NATURAL  LAW. 

1885-1890. 

§128.  Rydberg  on  the  Nature  of  Periodicity — §129.  Relations  be- 
tween the  Atomic  Weight  Differences  Observed  by  Rydberg — 
§130.  Reynolds’  Diagram  Representing  the  Periodic  Law — 
§131.  Crookes’  Modification  of  this  Diagram — §132.  Crookes’ 
Genesis  of  the  Elements — §133.  Dulk  upon  Gravitation  and 
the  Atomic  Weights — §134.  Pliipson’s  Outlines  of  a newT  Atomic 
Theory — §135.  Reed’s  Graphical  Representation  of  the  Rela- 
tion between  Valence  and  Atomic  Weight — §136.  Griinwald’s 
Mathematical  Spectrum  Analysis — §137.  Ames’  Criticism  of 
Griinwald — §138.  Griinwald’s  Definition  of  Chemical  Atoms — 
§139.  Thomsen’s  Views  as  to  Unity  of  Matter — §140.  Flavitz- 
ky’s  Functions  for  Periodicity — §141.  Numerical  Regularities 
observed  by  Bazaroff — §142.  Livermore’s  Classification — §143. 


TABLE  OF  CONTENTS. 


Vll 


An  Atomic  Hypothesis  by  Pearson— §144.  Stoney’s  Logarith- 
mic Law  of  the  Atomic  Weights — §145.  New  Relations  between 
the  Atomic  Weights  by  Delauney — §146.  Haughton’s  Geomet- 
rical Illustration  of  the  Periodic  Law — §147-  Hartley’s  Defini- 
tion of  Atomic  Weight — §148.  Stransky’s  Numerical  Relations 
— §149.  Remsen  on  the  Nature  of  the  Elements — §150.  Mende- 
leeff’s  Faraday  Lecture — §151.  Buehler’s  Theory  as  to  the  Na- 
ture of  Matter 181-232 


CHAPTER  EIGHTH. 

THE  DEVELOPMENT  OF  THE  NATURAL  LAW. 

1890-1896. 

§152.  The  Controversy  over  the  Standard — §153.  Kronberg’s  Iso- 
morphism of  the  Atoms — §154.  Tchitcherine’s  System— §155. 
Sutherland’s  New  Periodic  Property — §156.  Carnelley’s  Alge- 
braic Expression  of  the  Periodic  Law — §157.  Wendt’s  Evolu- 
tion of  the  Elements — §158.  Bassett’s  Tabular  Expression  of 
the  Periodic  Relations — §159.  Wilde  on  the  Origin  of  the  Ele- 
ments— §60.  New  Numerical  Relations  by  Adkins — §161.  Meu- 
sel  on  the  Oneness  of  the  Elements — §162.  Preyer’s  Genetic 
System — §163.  Wislicenus  on  the  Nature  of  Matter — §164.  A 
New  Periodic  Table  by  Deeley — §165.  Palmer’s  Views  as  to  the 
Nature  of  the  Elements — §166.  Meyer  on  the  use  of  the  Sys- 
tem by  Teachers — §167.  Hinrich’s  True  Atomic  Weights — §168. 
Rang’s  Periodic  Arrangement — §169.  A New  System  by  Traube 
— §170.  Venable’s  Modified  Arrangement — §171.  Thomsen’s  Ra- 
tional Atomic  Weights — §172.  Thomsen’s  Systematic  Group- 
ing of  the  Elements — §173.  Thomsen’s  Group  of  Inactive  Ele- 
ments— §174.  The  System  of  de  Boisbaudran — §175.  Blan- 
shard’s  Cross  Analogies — §176.  Solubility  and  Genesis  of  the 
Elements — §177.  The  Melting  Points  as  a Clue  to  Genesis — 
§178.  The  Position  of  Argon  and  Helium  in  the  System — §179. 
Victor  Meyer  on  the  Problems  of  the  Atoms — §180.  Lothar 
Meyer’s  Account  of  the  Inception  of  the  Periodic  System — 


TABLE  OF  CONTENTS. 


viii 

§181.  Lea  on  the  Color  of  the  Ions — §182.  Flavitzky’s  Function 
for  Deduction  of  Properties — §183.  Tutton’s  Comparison  of  Iso- 


morphous  Salts 233-284 

Index  to  Literature 285-308 

List  of  Authors 309-312 

General  Index 313-321 


PREFATORY  SKETCH. 


This  work  is  intended  as  a study  of  the  development 
of  the  natural  law  underlying  the  relations  of  the  ele- 
ments and  their  properties  to  one  another.  It  is  to  be 
used  for  purposes  of  reference  and  of  study  and  not  as  a 
mere  history  of  the  subject.  The  errors  and  repetitions 

t 

of  the  writers  upon  this  subject  in  the  past  few  years 
have  abundantly  proved  the  necessity  for  some  such 
gathering  and  systematizing  of  the  work  of  former  years. 
It  is,  in  the  main,  an  out-of-the-way  sort  of  literature 
and  the  difficulty  of  gathering  it  increases  with  the  lapse 
of  time.  The  growing  interest  in  this  natural  law 
speaks  well  for  the  progress  of  the  science  in  the  future. 
More  and  more  it  is  becoming  recognized  as  the  basis  of 
the  science,  and  the  hope  of  the  solution  of  some  of  the 
greatest  problems  which  the  chemist  has  to  face  seems 
to  lie  in  it.  The  reproach  that  chemistry  is  not,  in  the 
fullest  sense,  a science  will  continue  just  so  long  as 
chemists  content  themselves  with  raking  together  the 
straws  of  facts,  gleaners  many  of  them  in  a harvested 
field,  and  neglect  the  “weightier  matters  of  the  law.’’ 
The  gathering  of  facts  is  good,  gleaning  is  good,  but 
contentment  with  such  gains  means  stagnation. 

The  task  has  been  undertaken  in  the  hope  of  arousing 
interest  in  this  matter  and  of  aiding  in  the  further  de- 
velopment of  the  still  incomplete  system.  No  excuses 
are  offered  for  the  imperfections  of  the  work.  It  could 
not  be  other  than  imperfect.  The  task  has  been  most 


2 


PREFATORY  SKETCH. 


difficult,  and  the  limitations  of  the  writer  have  been  felt 
at  every  turn.  It  has  been  done  as  conscientiously  and 
impartially  as  was  possible.  Doubtless  many  authors 
will  find  cause  for  disagreement  with  the  treatment  ac- 
corded their  work.  The  reception  of  Newland’s  Law  of 
Octaves,  by  the  London  Chemical  Society,  and  many 
other  instances  of  mistaken  judgment,  show  how  difficult 
it  is  to  weigh  these  matters  fairly  and  wisely. 

Since  there  may  be  some  who  do  not  care  to  make  a 
study  of  the  whole  subject,  but  would  like  to  take  a con- 
nected glance  over  it,  this  preface  will  be  turned  into  an 
historical  sketch  of  the  law’s  development,  omitting  the 
mass  of  details  to  be  found  in  the  remainder  of  the  work. 
Such  a sketch  may  prove  useful  to  others  also. 

Before  the  atomic  theory  was  formulated,  numerical 
relations  were  proposed  by  Richter,  the  founder  of  Stoi- 
chiometry, between  the  equivalents  obtained  by  him  for 
the  various  bases  and  acids.  This  mathematical  work 
of  his  served  but  little  purpose  beyond  bringing  the 
whole  subject  of  his  equivalents  into  some  disrepute. 
Only  a few  years  passed  after  the  publication  of  the  first 
tables  of  atomic  weights  before  their  inter-relation  be- 
came a subject  of  speculation  and  research.  In  1815  we 
have  Prout  pointing  out  the  strange  fact  of  their  close 
approximation  to  whole  numbers  and  boldly  rounding 
them  off  into  such.  If  they  were  integral  multiples  of 
hydrogen,  he  reasoned,  then  this  might  be  the  primal 
matter  and  all  elements  made  up  of  it.  The  “ Multi- 
plen-fieber”  quickly  took  possession  of  the  chemical 
world,  even  of  conservative,  level-headed  workers  such 


PREFATORY  SKETCH. 


3 


as  Berzelius.  Enthusiastic  support  was  given  it  by  the 
English  chemists  especial^  and,  when  Berzelius  after- 
wards became  its  great  antagonist,  Thomson  and  others 
busied  themselves  in  its  defense.  The  newly  organized 
British  Association  devoted  its  fresh  energies  to  an  exam- 
ination into  the  condition  of  the  various  sciences  and, 
among  other  inquiries,  set  on  foot  one  as  to  the  grounds  for 
believing  in  what  was  then  called  and  has  been  often  so 
called  since,  Prout’s  Law.  The  result  of  this  inquiry 
was  adverse  to  the  ‘ ‘ law’  ’ and  it  would  have  been 
dropped,  in  all  probability,  had  it  not  been  taken  up  by 
Marignac,  Dumas,  and  the  French  chemists,  with  cer- 
tain modifications  rendered  necessary  by  the  more  per- 
fect knowledge  of  the  atomic  weights.  Probably  no 
other  hypothesis  in  chemistry  has  been  so  fruitful  of 
excellent  research  as  this  much  discussed  hypothesis  of 
Prout. 

Meanwhile,  a different  style  of  numerical  regularity 
had  been  brought  to  the  notice  of  chemists.  In  1817, 
Dobereiner  first  noticed  a strange  grouping  of  analogous 
elements  into  threes,  or  triads  as  they  soon  came  to  be 
called.  The  intermediate  member  of  such  a triad 
showed  itself  to  be  a mean  of  the  other  two  in  atomic 
weight  and  other  properties.  Dobereiner  was  at  first  in- 
clined to  think  that  this  could  only  mean  that  the  inter- 
mediate element  was  a compound  of  the  other  two.  His 
effort  at  arranging  all  of  the  elements  into  triads  failed. 
Still  he  did  the  science  great  service  in  arranging  the 
elements  aceordingto  their  analogies  andtosome  extent  ac- 
cording to  their  atomic  weights.  It  was  a great  lightening 


4 


PREFATORY  SKETCH. 


of  the  task  of  both  teacher  and  student  and  hence  found 
ready  entrance  into  the  text-books,  especially  that  of 
Leopold  Gmelin,  the  most  influential  chemical  writer  of 
the  times. 

For  twenty  years,  little  was  added  to  the  work  of 
Dobereiner.  Little  could  be  done  with  the  imperfect 
and  incomplete  tables  of  the  atomic  weights  then  in  use. 
Dumas  and  others  had  been  busy  in  the  revision  of 
many  of  these  constants  and  his  mind  was  thus  espec- 
ially drawn  to  their  numerical  regularities.  At  the 
meeting  of  the  British  Association  at  Ipswich  in  1851, 
he  delivered  a lecture,  embodying  his  ideas  as  to  the 
possible  composite  nature  of  the  elements  and  giving  in- 
stances of  remarkable  relations  existing  between  their 
atomic  weights.  This  attracted  the  earnest  attention  of 
chemists  everywhere.  Reports  of  the  lecture  were  pub- 
lished in  the  scientific  journals  of  various  countries. 
Hopes  were  aroused  in  very  conservative  chemists  that 
the  dissociation  of  the  so-called  simple  bodies,  which  for 
half  a century  had  been  looked  upon  as  made  up  of  un- 
decomposable  atoms,  was  a possible  achievement  of  the 
near  future.  It  would  transport  one  to  dreamland  at 
once  to  think  of  what  could  be  accomplished  if  once  the 
secret  of  the  composition  and  dissociation  of  these  ele- 
ments was  in  the  grasp  of  the  chemist. 

A diligent  company  of  thinkers,  workers,  and  also 
visionary  speculators  sprang  up.  The  most  prominent 
characteristic  of  the  work  of  the  period  wTas  the  digging 
out  of  arithmetical  regularities  and  relations  between  the 
numbers  representing  the  atomic  weights.  Strict  accord 


PREFATORY  SKETCH. 


5 


was  not  demanded.  Approximations  ruled  the  day,  and 
the  reputed  laws  discovered  were  justified  by  the  appeal 
to  the  laws  of  probabilities.  It  was  easy  to  calculate 
out,  as  De  Morgan  did,  that  the  probabilities  were 
greatly  against  such  and  such  a number  of  approximate 
coincidences  occurring  by  accident.  But  little  attention 
was  paid  to  the  other  properties  of  the  elements  and 
their  connection  with  the  atomic  weights,  though  in 
many  cases  the  isomorphism  of  salts  was  made  use  of  as 
determining  the  analogies  of  the  elements.  The  triads  of 
Dobereiner  were  completed  and  pushed  far  beyond  the 
speculations  of  their  author.  There  were  efforts  at  com- 
bining them  into  enneades  and  securing  a net- work  of 
elements.  Algebraic  formulas  were  sought  for,  by 
means  of  which  it  would  be  possible  to  calculate  the 
various  atomic  weights.  The  regularities  observed 
among  the  homologous  series  of  organic  chemistry  were 
appealed  to  in  the  hope  of  solving  the  mystery  of  the 
singular  regularities  which  undoubtedly  existed.  For 
one  must  not  think  of  these  workers,  some  of  them  chem- 
ists of  great  reputation,  as  being  entirely  misled.  Of 
course  a great  variety  of  relations  are  always  to  be  ob- 
served between  sixty  odd  numbers  taken  out  of  a little 
more  than  two  hundred,  especially  if  one  is  not  over  partic- 
ular in  insisting  upon  exact  coincidences.  There  are  in- 
teresting numerical  relations  actually  existing  between 
these  atomic  weights,  first  noticed  at  the  time  of  which  we 
are  speaking  and  still  without  any  plausible  explanation. 

In  this  period  will  be  found  the  triads  of  Kremers, 
Lennsen,  and  Odling  ; the  homologous  series  of  Cooke, 


6 


PREFATORY  SKETCH. 


Dumas,  and  Mercer  ; the  double  parallelism  of  Dumas; 
and  the  atomic  weight  differences  of  Dumas,  Pettenkofer, 
and  Lea.  There  was  also  the  first  attempt  at  arranging 
the  atomic  weights  in  an  ascending  series  according 
to  their  increasing  magnitude.  This  was  by  Gladstone, 
and  is  looked  upon  now  as  one  of  the  fundamental  fea- 
tures of  the  periodic  system.  No  results  were  obtained 
at  that  time  by  this  arrangement  because  the  atomic 
weights  used  were  very  faulty,  a large  number  of  them 
being  placed  at  about  half  the  values  at  present  assigned 
to  them.  It  is  not  surprising  that  the  hopes  first 
aroused  as  to  any  valuable  results  flowing  from  these 
speculations  were  disappointed,  and  with  the  disap- 
pointment seems  to  have  come  a general  discrediting  in 
the  public  mind  of  all  such  work.  Chemists  of  note  ap- 
parently dropped  the  subject,  some  wrote  anonymously, 
and  really  meritorious  work  was  received  either  with 
silence  or  ridicule.  It  is  only  just  to  state  that,  so  far 
as  any  hopes  of  the  immediate  solution  of  the  problem 
of  the  constitution  of  the  elements  was  concerned,  Dumas 
had  been  careful  to  discourage  them. 

The  first  gleam  of  hope  of  an  improved  condition  of 
affairs  came  through  the  introduction  of  more  accurate 
atomic  weights  by  Cannizzaro.  Williamson  aided  in 
the  introduction  of  these  in  England.  With  these  it 
became  possible  to  see  relations  which  had  been  ob- 
scured before.  An  arrangement  of  the  atomic  weights 
in  an  ascending  series  now  revealed  something  of  that 
periodicity  which  has  since  proved  such  a valuable 
thought  to  inorganic  chemistry.  The  first  to  arrange 


PREFATORY  SKETCH. 


7 


them  in  this  way  was  the  French  engineer  and  mineralo- 
gist de  Chancourtois.  His  Telluric  Screw  contained 
much  of  the  essential  truth  that  lies  in  the  periodic  law. 
Along  with  it,  there  was  of  course,  error  and  confusion 
with  useless  detail.  It  is  easy  to  see  in  this,  now,  the 
germs  of  Me-ndeleeff’s  later  discovery.  Chemists  of  the 
day,  however,  were  not  in  a position  to  sift  out  the  false, 
and  hence  the  whole  scheme  received  little  or  no  atten- 
tion, and  remained  hidden  in  the  publications  of  the 
French  Academy  of  Sciences,  to  be  unearthed  a quarter 
of  a century  afterwards,  by  two  French  chemists. 

Following  this  came  the  presentation  of  the  Law  of 
Octaves  by  Newlands,  before  the  London  Chemical  So- 
ciety. Here  the  ascending  series  and  the  periodicity 
were  still  more  clearly  brought  out.  There  was  much 
less  of  the  false  and  less  of  confusing  detail.  A thought, 
which  was  largely  lacking  in  the  work  of  the  previous 
decade,  begins  to  appear  here.  That  is,  the  dependence 
of  the  properties  upon  the  atomic  weights.  The  same  is 
true  of  the  system  of  de  Chancourtois.  And  yet,  possi- 
bly because  of  the  fanciful  name  given  by  Newlands  im- 
plying a unity  of  his  system  with  that  of  music,  the  So- 
ciety accorded  him  chiefly  ridicule  for  his  effort,  and  it 
took  them  twenty  years,  or  more,  to  find  out  their  mis- 
take. 

Almost  at  the  same  time  with  the  announcement  of 
Newland’s  law,  Meyer  published  his  first  work  upon  the 
Modern  Theories  of  Chemistry,  a work  destined  to  a 
life  of  many  editions  and  much  fame  and  usefulness,  and 
in  this  he  gave  the  first  of  his  tables  of  the  atomic 


8 


PREFATORY  SKETCH. 


weights,  the  precursor  of  his  periodic  system.  This 
certainly  failed  to  give  even  as  clear  an  idea  of  periodi- 
city as  the  table  of  Newlands,  and  required  a great  deal 
of  evolution  before  it  could  bear  much  resemblance  to 
the  completed  table.  Almost  at  the  same  time  we  have 
the  announcement  by  Hinrichs  that  the  properties  of  the 
elements  are  functions  of  their  atomic  weights  and  that 
the  unity  of  matter  was  as  real  as  the  unity  of  force. 
These  were  the  precursors  of  the  periodic  law.  They 
failed  of  recognition  for  many  reasons,  though  two  chief 
ones  can  be  assigned  ; first  the  public  was  wearied  with, 
and  distrustful  of,  such  speculations ; second!}’,  they 
were  incomplete,  and  in  some  respects,  overweighted 
with  error. 

When  Mendeleeff,  in  1869,  announced  the  new 
“Natural  System,'’  as  he  at  first  called  it,  one  keen- 
sighted  observer  reported  it  as  something  that  would 
prove  interesting  and  probably  useful,  but  no  great  stir 
was  created,  such  as  was  noticed  at  the  delivery  of  Du- 
mas’ address.  In  a very  short  time  appeared  the  almost 
identical  system  of  Meyer,  evolved  from  his  earlier  tables 
but  modified  somewhat  by  his  study  of  the  table  of  Men- 
deleeff. To  these  two  men  the  Royal  Society  of  Eng- 
land gave  the  highest  medal  in  its  gift  as  the  discoverers 
of  the  greatest  law  of  modern  chemistry.  To  one,  or 
both,  the  credit  undoubtedly  belongs.  They  were  both 
in  ignorance  of  the  previous  work  of  de  Ehancourtois 
and  of  Newlands  and  they  presented  the  system  in  such 
a shape  that  it  was  useful  for  many  purposes  and  could 
be  put  to  the  test  as  to  its  truth  and  value.  Still  the 


PREFATORY  SKETCH. 


9 


system  aroused  little  comment  and  was  threatened  with 
the  same  fate  of  dust  and  oblivion  which  had  befallen 
the  systems  of  earlier  writers.  After  several  years  of 
neglect,  even  on  the  part  of  its  authors,  attention  was 
drawn  to  the  system  once  more  by  the  fortunate  fulfil- 
ment of  certain  bold  predictions  made  by  Mendeleeff  in 
his  table.  The  discovery  of  scandium  and  gallium  and 
their  fitting  into  the  predicted  places,  with  atomic 
weights  and  other  properties  coinciding  with  those  pre- 
dicted for  them,  gave  a newimpetusto  the  study  of  these 
tables  and  their  use  in  the  class-room.  Many  results 
have  sprung  from  this.  Increased  diligence  has  been 
observed  in  the  revision  of  faulty  atomic  weights  ; new 
interest  has  been  shown  in  the  advancement  of  the 
knowledge  of  inorganic  chemistry ; the  inter-relation  of 
the  elements  has  become  so  clear  that  one  is  forced  to 
the  conclusion  that  they  are  composite  in  nature,  even 
though  the  nature  of  the  relationship  is  unknown,  and 
no  immediate  hope  is  held  out  of  solving  the  problem. 
The  question  of  the  variability  of  the  atomic  weights, 
suggested  by  Marignac  and  discussed  by  Cooke,  Schiitz- 
enberger,  Boutlerow,  and  others,  seems  untenable  in  the 
light  of  the  periodic  system  and  so  too  with  the  hypothe- 
sis of  Prout,  at  least  in  its  original  form,  presenting 
hydrogen  as  the  original  element.  This  hypothesis  had 
been  laid  to  rest  by  the  wonderfully  accurate  atomic 
weight  determinations  of  Stas,  but  was  revived  again  by 
its  old  defender,  Dumas,  to  receive  a fitful  sort  of  dis- 
cussion for  a few  years  and  be  accorded  a tentative,  half- 
way support  on  the  part  of  a few  distinguished  chemists. 


IO 


PREFATORY  SKETCH. 


Its  original  features  have  now  been  lost  and  it  has  be- 
come identified  with  the  theory  of  the  unity  of  matter 
and  the  idea  of  the  composite  nature  of  the  elements.  In 
this  form  it  is  simply  one  of  the  natural  deductions  from 
the  periodic  law,  although  Mendeleeff  would  discourage 
all  such  dreams  and  denies  that  they  are  to  be  justly  de- 
duced from  his  law. 

Those  who  read  the  later  pages  of  this  work  will  see 
how  far  from  complete  this  periodic  system  is.  Its  im- 
perfections are  many,  but  they  are  outweighed  by  its 
virtues  and  the  truths  which  it  so  well  presents.  That 
there  can  be  a better  presentation  of  them  is  most  likely ; 
that  it  is  just  beginning  to  reveal  all  of  the  truths  which 
it  is  capable  of  revealing  is  also  true.  It  demands  of  the 
chemist  careful  study.  The  close  of  this  century  calls 
loudly  for  another  Lavoisier,  who  shall  interpret  the  facts 
won  by  such  hard  toil  and  place  the  science  on  the  right 
track  for  another  century  of  brilliant  progress  and  dis- 
covery. 


The  Development  of  the  Periodic  Law. 


CHAPTER  I. 

i.  Prout’s  Hypothesis  and  Doebereiner’s  Triads. — 

The  study  of  the  development  of  the  natural  arrange- 
ment of  the  elements,  the  gradual  crystallization  of  the 
ideas  concerning  the  laws  underlying  the  numerical  re- 
lations of  the  atomic  weights  into  definite  form,  is  one  of 
great  importance  to  the  science  of  chemistry.  Like 
other  secrets  wTrested  from  nature,  this  has  been  no  sud- 
den discovery,  but  is  the  result  of  the  thought  and  labor 
of  many  years.  In  speaking  of  this  development,  it 
should  be  clearly  understood  that  it  is  not  to  be  consid- 
ered complete,  nor  that  the  process  of  evolution  is  fin- 
ished, nor  that  the  natural  system  stands  before  us 
to-day  in  its  full  and  perfect  form.  Much  progress  has 
been  made,  but  there  is  growth  in  these  ideas,  and  hence 
it  is  incumbent  upon  chemists  to  make  a more  thorough 
study  of  what  has  been  done  and  so  prepare  themselves 
to  aid  in  further  progress.  The  natural  system  has 
already  become  the  central  fact  of  the  science.  It  has 
dispelled  many  errors,  it  has  inspired  much  true  work, 
it  points  to  the  solution  of  some  of  the  greatest  problems 
which  we  have  to  face. 

The  study  of  this  development  will  be  pursued  chron- 
ologically, and  though  there  is  at  times  much  tempta- 
tion to  follow  up  some  special  idea,  as  that  of  the  triads, 
and  bring  together  in  one  place  all  work  referring  to  it, 


12 


THE  PERIODIC  UW. 


there  will  be  only  a few  brief  excursions  of  the  kind. 

It  would  seem  that  there  is  some  great  fascination  con- 
nected with  the  search  after  numerical  relations  among 
the  atomic  weights.  From  the  very  first  the  possible  dis- 
covery of  some  mysterious  law  or  the  dream  of  the  Unity 
of  Matter  has  lured  on  investigators  and  dreamers. 
Prout  was  the  first  one  to  point  out  a numerical  relation 
on  which  he  based  his  famous  hypothesis.  To  show  the 
material  with  which  he  worked,  it  will  be  necessary  to 
discuss  the  early  tables  of  atomic  weights. 

2.  The  Unity  of  Matter. — The  question  as  to  the  na- 
ture of  matter  is  one  of  the  great  world-problems  con- 
stantly attracting  and  eluding  man’s  research.  For 
centuries  the  mind  of  man  has  dwelt  on  this  problem 
without  success,  beyond  certain  plausible,  yet  unsatis- 
factory speculations,  and  still  he  is  not  willing  to  give 
up  the  problem  as  one  beyond  his  powers  of  solution. 
The  trend  of  thought  has  been  toward  simplification, 
a reduction  of  matter  to  its  simple  components  and  a 
unification  in  one  primal  component  if  possible,  thus 
bringing  matter  into  line  with  the  great  unities  of  the 
universe. 

The  Greek  dream  of  atoms  has  found  justification  and 
fulfilment  in  the  research  and  learning  of  this  century. 
The  old-world  idea  of  unity  or  of  a primal  element  has 
its  followers  at  the  present  day  who  believe  we  are  verg- 
ing upon  such  discoveries  as  will  confirm  that  also,  going 
deeper  into  the  nature  of  matter  than  the  material,  pon- 
derable atoms.  This  is  a close  approach  to  the  Pytha- 


DEFINITION  OF  ELEMENT. 


13 


gorean  idea  of  the  infinite  divisibility  of  matter  yet 
should  not  be  confused  with  it  as  some  have  done. 

Dalton’s  revival  of  the  atomic  hypothesis  at  the  begin- 
ning of  this  century  gave  additional  meaning  and  im- 
portance to  Lavoisier’s  definition  of  the  elements,  and 
from  that  time  we  have  these  two  ideas,  element  and 
atoms,  forming  the  very  basis  of  the  science  of  chemis- 
try. These  ideas  have  not  been  introduced  without 
some  opposition,  some  confusion  and  lack  of  clearness  of 
definition,  but  they  have  successfully  fought  their  way 
and  become  more  clearly  defined. 

As  the  century  draws  to  its  close  the  thought  is  gain- 
ing ground  that  these  elements  are  not  really  simple 
bodies,  but  that  their  material  atoms  are  composed  of 
other  forms  of  matter,  and  the  hope  rises  that  through 
these  the  way  may  be  traced  to  the  old  elusive  primal 
matter. 

3.  Definition  of  Element. — With  increasing  knowl- 
edge the  exact  definition  of  an  element  has  become  more 
and  more  difficult.  The  observation  of  the  phenomena 
of  allotropism  overthrew  the  older  definitions.  Perhaps 
the  one  given  by  Patterson  Muir  (218,  p.  6)1  is  the  most 
satisfactory.  “The  notion  of  the  elements  that  has  been 
attained  after  long  continued  labor  is  that  of  certain 
distinct  kinds  of  matter,  each  of  which  has  properties 
that  distinguish  it  from  every  other  kind  of  matter,  no 
one  of  which  has  been  separated  into  portions  unlike 
one  another  and  unlike  the  original  substance,  and 

1 The  figures  in  parentheses  refer  to  Index  to  literature  at  the  end  of  the 
volume. 


14 


THE  PERIODIC  LAW. 


which  combine  together  to  produce  new  kinds  of 
matter  that  are  called  compounds.”  Again  he  speaks 
of  the  term  being  used  more  and  more  to  designate 
certain  groups  or  assemblages  of  associated  properties 
(218,  p.  31).  It  is  one  of  the  objects  of  these  pages  * 
to  sum  up  all  that  has  been  said  about  the  numerical 
inter-relations  of  the  atoms  of  these  elements,  and  show 
just  how  much  ground  the  speculations  as  to  a primal 
matter  have  for  their  basis.  The  literature  on  the  sub- 
ject is  difficult  of  access  ; there  much  is  ignorance  as  to 
this  literature,  and  a knowledge  of  it  may  save  chemists 
from  much  repetition  and  from  useless  vagaries. 

4.  The  Atomic  Weights  of  Dalton. — The  concluding 
paragraph  of  a paper  read  by  Dr.  John  Dalton  before  the 
Literary  and  Philosophical  Society  of  Manchester,  Octo- 
ber 21,  1803,  upon  “The  Absorption  of  Gases  by  Water 
and  other  Liquids”  is  as  follows  : 

“The  greatest  difficulty  attending  the  mechanical  hy- 
pothesis, arises  from  different  gases  observing  different 
laws.  Why  does  water  not  admit  its  bulk  of  every  gas  alike  ? 
This  question  I have  duly  considered,  and  though  I am  not 
yet  able  to  satisfy  myself  completely,  I am  nearly  persua- 
ded that  the  circumstance  depends  upon  the  weight  and 
number  of  the  ultimate  particles  of  the  several  gases, 
those  whose  particles  are  lightest  and  single  being  least 
absorbable,  and  the  othq(t-s  more,  accordingly  as  they  in- 
crease in  weight  and  complexity.  (Subsequent  exper- 
ience renders  this  conjecture  less  probable) . An  inquiry 
into  the  relative  weights  of  the  ultimate  particles  of 
bodies  is  a subject,  as  far  as  I know,  entirely  new:  I 


THE  ATOMIC  WEIGHTS. 


15 


have  lately  been  prosecuting  this  inquiry  with  remarkable 
success.  The  principle  cannot  be  entered  upon  in  this 
paper:  but  I shall  just  subjoin  the  results,  as  far  as  they 
appear  to  be  ascertained  by  my  experiments.” 

DALTON’S  “TABLE  OF  THE  RELATIVE  WEIGHTS  OF  THE  ULTIMATE 
PARTICLES  OF  GASEOUS  AND  OTHER  BODIES.” 


Hydrogen  1.0 

Azot 4.2 

Carbone 4.3 

Ammonia 5.2 

Oxygen 5.5 

Water 6.5 

Phosphorus 7.2 

Phosphoretted  hydrogen 8.2 

Nitrous  gas 9.3 

Ether 9.6 

Gaseous  oxide  of  carbone 9.8 

Nitrous  oxide 13.7 

Sulphur 14.4 

Nitric  acid 15.2 

Sulphuretted  hydrogen 15.4 

Carbonic  acid 15.3 

Alcohol 15. 1 

Sulphureous  acid 19.9 

Sulphuric  acid 25.4 

Carburretted  hydrogen  from  stagnant  water  6.3 

Olefiant  gas 5.3 


This  was  the  first  attempt  at  a table  of  the  atomic 
weights.  Elements  and  compounds  are  considered  to- 
gether and  the  numbers  given  are,  of  course,  very  faulty. 
Richter’s  earlier  table  of  the  equivalents  of  various  sub- 
stances can  scarcely  be  considered  in  the  same  light  as 


i6 


THE  PERIODIC  LAW. 


Dalton’s.  These  were  mainly  acids  and  bases  and  it  was 
purely  a stoiehiometrical  table. 

In  the  year  1808  appeared  Dalton’s  New  System  of 
Chemical  Philosophy . In  this  he  gives  a table  of  the, 
atomic  weights  of  thirty-seven  substances,  again  taking 
hydrogen  as  the  unit  and  standard. 

5.  Remarks  of  Roscoe  on  Dalton’s  First  Table  of 
Atomic  Weights. — Doubtless  many  chemists  have  won- 
dered how  these  first  atomic  weights  were  determined. 
Dalton’s  paper  was  read,  as  w7e  have  seen,  before  the 
Manchester  Literary  and  Philosophical  Society  on  Oc- 
tober 21,  1803,  and  was  published  in  1805.  There  is  rea- 
son to  believe  that  the  numbers  were  obtained  after  the 
paper  was  read,  says  Roscoe  (93),  and  inserted  before  its 
publication.  Dalton  gives  no  detailed  explanation  of 
how  these  actual  numbers  were  arrived  at. 

In  1810,  in  his  New  System  of  Chemical  Philosophy , -he 
explains  in  some  cases  how  he  arrived  at  these  weights 
but  he  had  then  made  considerable  changes  in  the  num- 
bers. 

Roscoe  very  ingeniously  attempts  to  trace  the  origin  of 
these  original  numbers.  He  is  struck  by  the  clearness 
of  perception  of  truth  which  enabled  him  to  argue  cor- 
rectly from  inexact  experiments.  “ In  the  notable  case, 
indeed  in  which  Dalton  announces  the  first  instance  of 
combination  in  multiple  proportions  the  whole  conclusion 
is  based  upon  an  erroneous  experimental  basis.  If  we 
repeat  the  experiment,  as  described  by  Dalton,  we  do  not 
obtain  the  results  he  arrived  at.  We  see  that  Dalton’s 


TABLES  OF  THOMSON  AND  WOLLASTON. 


17 


conclusions  were  correct,  although  in  this  case  it  appears 
to  have  been  a mere  chance  that  his  experimental  results 
rendered  such  a conclusion  possible.” 

6.  The  Tables  of  Thomson  and  Wollaston. — In  1810 
Thomson  gave  in  his  System  of  Chemistry , a table  of 
the  equivalents  for  23  acids  and  bases.  Wollas- 
ton’s Table  of  Equivalents  published  in  1814  was  a de- 
cided improvement  upon  the  preceding,  as  he  made  use 
of  the  best  available  work  of  other  chemists,  notably  of 
Berzelius.  Instead  of  taking  hydrogen  as  the  standard, 
he  used  oxygen  giving  it  the  equivalent  10. 

WOLLASTON’S  TABLE,  1814. 

Hydrogen 1.32 

Oxygen 10.00 

Water 11.32 

Carbon 7.54 

Sulphur 20.00 

Phosphorus 17.40 

Nitrogen r7-54 

Chlorine 44.1 

Oxalic  acid 47-0 

Ammonia 21.5 

Sodium 29.1 

Potassium 49.1 

Magnesia 24.6 

Calcium 25.46 

Strontium 63.0 

Baryta 97.0 

Iron  34.5 

Copper 40.0 

Zinc - 41.0 

Mercury I25-5 

Lead 129.5 

Silver 135.0 


i8 


THE  PERIODIC  LAW. 


Only  the  most  important  of  the  equivalents  are  given 
in  the  above  table  as  selected  by  Kopp.1  Elements  and 
compounds  are  given  together,  Wollaston  declining  to 
consider  these  as  atomic  weights  and  desiring  to  avoid 
the  difficulties  and  inconsistencies  of  Dalton’s  rules.  < 

7.  The  Table  of  Berzelius. — Between  the  years  1810 
and  1818  Berzelius  published  in  the  Memoirs  of  the 
Stockholm  Academy  a number  of  determinations  of 
atomic  weights.  His  first  complete  table  was  published 
in  1815  and  was  as  follows  : 

tr 

BERZELIUS’  TABLE,  1815. 


Oxygen 100.0 

Phosphorus 167.5 

Fluorin 60.0 

Carbon 74.9 

Hydrogen 6.64 

Molybdenum 601.6 

Wolframium 2424.2 

Antimony 1613.0 

Platinum 1206.7 

Mercury  2531.6 

Copper 806.5 

Cobalt 732.6 

Lead 2597.4 

Iron 693.6 

Manganese 711.6 

Magnesium 315.5 

Strontium 1118. 1 

Sodium 579.3 

Sulphur 201.0 

Muriaticum 139-6 

Boron 73.3 


1 Gesch.,  11,  p.  376. 


THE  TWO  DIRECTIONS  OF  THE  WORK. 


19 


Berzelius’  Table,  1815.  (Continued.) 


Nitricum 79.5 

Arsenic 839.9 

Chromium 708.1 

Tellurium 806.5 

Silicon 304.3 

Gold 2483.8 

Silver 2688.2 

Nickel 733-8 

Bismuth 1 774.0 

Tin 1470.6 

Zinc 806.4 

Aluminium 343-0 

Calcium 510.2 

Barium 1709. 1 

Potassium 978-0 


In  this  table  the  bodies  muriaticum,  fluoricum,  and 
nitricum  are  hypothetical  bodies,  Berzelius  supposing 
that  by  union  with  oxygen  they  yielded  the  acids  hydro- 
chloric, hydrofluoric  and  nitric.  These  were  therefore 
left  out  of  the  table  given  by  Berzelius  in  1826,  and, 
furthermore,  he  introduced  many  corrections  in  this 
subsequent  table.  This  was,  then,  the  condition  of  the 
atomic  weights  and  represents  the  extent  of  the 
knowledge  concerning  them  when  the  first  speculations 
as  to  the  numerical  relations  existing  between  them  ap- 
peared and  the  first  hypothesis  based  on  these  was 
formed. 

8.  The  Two  Directions  of  the  Work. — The  knowl- 
edge of  these  important  constants  of  nature  led  very 
speedily  to  attempts  at  deducing  numerical  regular- 
ities and  relations  along  two  lines.  First  there  were 


20 


THE  PERIODIC  RAW. 


the  efforts  of  Prout  and  Meinecke  to  show  that  these 
numbers  were  all  multiples  of  one  common  unit  of 
weight : secondly,  Dobereiner  blazed  the  way  for  a 

host  of  followers  in  discovering  numerical  relationships 
between  the  atomic  weights  of  similar  elements  or  those 
of  the  same  family,  and  later  on  of  the  dissimilar  ones. 

9.  Prout’s  Hypothesis — In  the  year  1815,  there  ap- 
peared (1)  an  anonymous  article  upon  the  subject  of  the 
relations  between  the  specific  weights  of  bodies  in  the 
gaseous  condition  and  their  atomic  weights.  An  abstract 
of  this  article  follows  and  attention  is  especially  to  be 
drawn  to  the  modest  manner  in  which  the  author  pro- 
pounds his  theory. 

‘ ‘ The  author  of  the  following  essay  submits  it  to  the 
public  with  the  greatest  diffidence  ; for  though  he  has 
taken  the  utmost  pains  to  arrive  at  the  truth,  he  has  not 
such  confidence  in  his  abilities  as  an  experimentalist  as 
to  induce  him  to  dictate  to  others  far  superior  to  himself 
in  chemical  acquirements  and  fame.  He  trusts,  how- 
ever, that  some  one  will  undertake  to  examine  it  and 
thus  to  verify  or  refute  its  conclusions.  If  these  should 
be  proved  erroneous,  still  new  facts  may  be  brought  to 
light,  or  old  ones  better  established  by  the  investigation ; 
but  if  they  should  be  verified,  a new  and  interesting 
light  will  be  thrown  upon  the  whole  science  of  chemis- 
try.” 4 

His  observations  were  founded  on  Gay-Lussac’s 
‘‘Doctrines  of  Volumes.”  Three  tables  are  given: 
Table  I containing  the  specific  gravities  of  various  sub- 


PROUT’S  SECOND  PAPER. 


21 


stances,  H being  i,  O being  io,  etc.  Table  II  gives  the 
specific  gravities  of  the  compounds  with  oxygen.  Table 
III  gave  the  specific  gravities  of  the  compounds  with 
hydrogen. 

“I  had  often  observed  the  near  approach  to  round 
numbers  of  many  of  the  weights  of  the  atoms  before  I 
was  led  to  investigate  the  subject.  Dr.  Thomson  ap- 
pears also  to  have  made  the  same  remark.  It  is  also 
worthy  of  observation  that  the  three  magnetic  metals  as 
noticed  by  Dr.  Thomson,  have  the  same  weight,  which 
is  double  that  of  azote.  Substances  in  general  of  the 
same  weight  seem  to  combine  readily  and  somewhat  to 
resemble  one  another  in  their  nature.” 

‘‘On  a general  review  of  the  tables,  we  may  notice  : 
i.  That  all  the  elementary  numbers,  hydrogen  being 
considered  as  i,  are  divisible  by  4,  except  carbon,  nitro- 
gen and  barium,  and  these  are  divisible  by  2,  appearing 
therefore  to  indicate  that  they  are  modified  by  a higher 
number  than  that  of  unity  or  hydrogen.  Is  the  other 
number  sixteen  or  oxygen,  and  are  all  substances  com- 
pounded of  these  two  elements  ?” 

His  other  deductions  have  no  bearing  upon  the  mat- 
ter in  question. 

10.  Prout’s  Second  Paper. — In  1816,  Prout  published 
another  paper  (2)  correcting  a mistake  in  the  one  just 
quoted.  In  it  he  expresses  the  following  views : 

‘ ‘ If  the  views  we  have  ventured  to  advance  be  correct, 
we  may  almost  consider  the  npooTy  vXy  of  the  ancients 
to  be  iealized  in  hydrogen;  an  opinion  by-the-by,  not 


22 


THE  PERIODIC  LAW. 


altogether  new.  If  we  actually  consider  this  to  be  the 
case,  and  further  consider  the  specific  gravities  of  bodies 
in  their  gaseous  states  to  represent  the  number  of  vol- 
umes condensed  into  one,  or  in  other  words,  the  number 
of  the  absolute  weights  of  a single  volume  of  the  first 
matter  {npcoTy  vXy)  which  they  contain,  which  is  ex- 
tremely probable,  multiples  in  weight  must  always  indi- 
cate multiples  in  volume,  and  vice  versa , and  the  spe- 
cific gravities  or  absolute  weights  of  all  bodies  in  a 
gaseous  state  must  be  multiples  of  the  specific  gravity 
or  absolute  weight  of  the  first  matter  {npcoTy  v\y),  be- 
cause all  bodies  in  a gaseous  state  which  unite  with  one 
another,  unite  with  reference  to  this  volume.” 

It  soon  became  known  that  the  author  of  these  papers 
was  Dr.  William  Prout,  a physiciari,  and  afterwards  a 
chemical  author  of  some  prominence.  His  views 
attracted  general  attention  and  in  so  far  as  thejr  referred 
to  the  atomic  weights  being  multiples  of  that  of  hydro- 
gen, and  hence  hydrogen  being  the  primal  element,  they 
were  looked  upon  with  favor,  more  especiall}r  in  England. 

ii.  Berzelius  and  Gmelin  in  Connection  with  Prout’s 
Hypothesis. — The  hypothesis  of  Prout  was  supported  by 
Thomson  in  England,  and  it  soon  had  many  adherents. 
Thomson’s  experimentsin  supportof  it  (8)  were  very  un- 
satisfactory however,  and  rvere  insufficient  as  evidence  to 
confirm  it.  It  was  received  by  some  in  both  France  and 
Germany,  but  met  with  strong  opposition  on  the  part  of 
others,  and  was  especially  antagonized  by  Berzelius, 
(though  he  at  first  regarded  it  favorably) . Berzelius  gave 


EXAMINATION  OF  THE  SUBJECT  BY  TURNER.  23 

in  1825,  a table  of  carefully  determined  atomic  weights 
of  the  elements  which  differed  in  many  cases  widely 
from  those  used  by  Prout  and  Thomson.  He  also 
urged  very  strongly  against  the  practice  of  rounding  off 
the  fractions  of  atomic  weights  into  whole  numbers.  As 
Hoffman  says  : “He  could  not  persuade  himself  that 
the  numerical  relations  of  these  values  betokened  an 
inner  connection  of  the  elements  nor  yet  a common  ori- 
gin. On  the  contrary,  he  was  of  the  opinion  that  these 
apparent  relations  would  disappear  more  and  more  as 
these  values  were  more  accurately  determined.  For  him 
therefore,  there  existed  as  many  forms  of  matter  as  there 
were  elements  : in  his  eyes  the  molecules  of  the  various 
elements  had  nothing  in  common  with  one  another  save 
their  immutability  and  their  eternal  existence.” 

Yet  in  1827,  ( 10) Gmelin  gives  in  two  parallel  columns 
the  atomic  weights  of  Berzelius,  with  their  fractions 
(oxygen  being  taken  as  100),  and  the  same  weights 
rounded  off  into  the  whole  numbers  (hydrogen  being  the 
standard). 

He  adds  : “It  is  surprising  that  in  the  case  of  many 
substances  the  combining  weight  is  an  integral  multiple 
of  that  of  hydrogen,  and  it  may  be  a law  of  nature  that 
the  combining  weights  of  all  other  substances  can  be 
evenly  divided  by  that  of  the  smallest  of  them  all.” 

12.  Examination  of  the  Subject  by  Turner. — In 

1829,  (11)  Turner,  who  was  then  an  adherent  of  the 
hypothesis,  began  a revision  of  the  work  of  Thomson. 
Later,  in  1832,  he  was  specially  delegated  by  the  British 


24 


THE  PERIODIC  LAW. 


Association  to  inquire  into  and  report  upon  this  ques- 
tion. The  basis  of  the  work  of  Thomson  had  been  the 
determination  of  the  atomic  weight  of  barium.  This 
Trtrner  critically  revised  and  decided  that  Thomson’s 
work  was  erroneous  and  that  of  Berzelius  correct.  In 
Turner’s  report  in  1833  (12)  he  gave  up  the  support  of 
the  hypothesis. 

13.  Penny’s  Results. — In  1839  (13)  Penny  attacked 
this  question  from  a different  standpoint.  If  the 
atomic  weights  were  represented  by  whole  numbers, 
then  their  differences  should  also  be  integers.  In 
a series  of  experiments  upon  potassium  chlorate 
and  potassium  nitrate,  he  showed  that  this  was  not 
the  case.  He  withdrew  his  support  from  the  theory  and 
thus,  in  its  home,  it  was  losing  ground.  But  the  failing 
theory  was  destined  to  be  revived  and  brought  vigor- 
ously to  the  front  again  in  the  laboratories  of  France. 

14.  Dumas’  Adhesion  to  Prout’s  Hypothesis. — At 

this  time  a number  of  excellent  workers  were  busied 
upon  the  revision  of  the  atomic  weights.  Among 
them  may  be  mentioned  Pelouze,  Marignac,  Erdmann, 
Marchand,  Svanberg,  Peligot,  and  others.  In  many 
cases  the  numbers  obtained  by  them  did  not  differ  greatly 
from  whole  numbers,  and  influenced  by  their  work,  as 
well  as  by  his  own  numerous  determinations,  Dumas,  in 
1840,  revived  the  hypothesis  of  Prout.  His  views  were 
strengthened  in  1842  (14)  by  the  re-determination  of  the 
ratio  of  carbon  to  hydrogen,  carried  out  by  his  pupil 
Stas  and  himself,  which  was  shown  to  be  almost  exactly 


PROUT’S  LATER  VIEWS. 


25 


12:1.  This  was  followed  by  his  work  upon  oxygen  and 
nitrogen,  giving  their  ratios  as  very  nearly  16:1  and 
14  : 1 respectively. 

15.  The  Extension  of  the  Hypothesis. — The  atomic 
weight  of  chlorine  had  proved  a great  stumbling 
block  to  the  supporters  of  P rout’s  hypothesis.  No 
revision  changed  it  materially  from  35.5.  Copper 
and  lead  and  some  other  elements  gave  similarly  trouble- 
some fractions.  To  overcome  this  Marignac  suggested 
in  1844  that  half  the  atomic  weight  of  hydrogen  be  used 
as  the  unit  and  thus  bring  chlorine  within  the  list  of 
integral  multiples.  The  idea  was  taken  up  by  Dumas 
with  enthusiasm,  but  he  found  it  necessary  to  go  a step 
further  and  take  one-fourth  the  atomic  weight  as  the 
unit.  This  was  in  1858  and  will  be  spoken  of  later. 
Erdmann  and  Marchand  are  to  be  classed  among  the 
Proutians  at  this  time,  and  indeed,  according  to  Berze- 
lius (9-b)  specially  exerted  themselves  to  find  confirma- 
tory evidence  for  the  theory. 

16.  Prout’s  Later  Views. — It  is  interesting  to  quote 
from  a later  work  of  the  author  of  this  hypothesis 
(3,  p.  no)  and  see  how  his  views  stood  the  stress  of 
the  heavy  conflict  waged  for  and  against  them. 

“ It  may  be  observed  that  we  have  spoken  as  if  the 
atomic  weights  of  bodies  were  related  to  one  another  by 
multiple  and  were  all  multiples  of  some  common  unit. 
Now  this  opinion  has  been  maintained  by  some,  while  it 
has  been  denied  by  others,  who,  admitting  that  multiples 
in  weight  are  necessary  to  the  union  of  similar  molecules, 


26 


THE  PERIODIC  LAW. 


both  chemically  and  cohesively,  will  not  admit  that  mul- 
tiples are  necessary  to  the  union  of  dissimilar  molecules. 
The  matter  is  one  which  in  the  present  imperfect  state 
of  chemistry,  can  hardly  be  determined  by  experi- 
ment ; for  what  with  the  difficulty  or  rather  impossibilit}^ 
of  procuring  bodies  in  a perfectly  isolated  form,  and  the 
unavoidable  imperfections  of  all  chemical  processes,  we 
can  scarcely  hope  to  approach  within  the  necessary 
limits  of  precision.” 

17.  The  Views  of  Heinecke.  — Meinecke  has  been 
mentioned  by  some  as  having,  independently  of  Prout, 
announced  the  same  views  at  about  the  same  time. 
This  may  have  arisen  from  the  fact  that  Ostwald,  in 
the  first  edition  of  his  ‘‘Allgemeine  Chemie,”  refers  to 
Meinecke’s  ‘‘Chemische  Messkunst,”  wffiich  was  pub- 
lished in  1815.  The  proper  citation  is  given  in  the 
second  edition  of  this  work  and  refers  to  a period 
three  years  later.  The  citation  (4)  is  as  follows  : 

‘ ‘ It  is  noteworthy  that  the  number  of  hydrogen  is  a 
divisor  of  the  remaining  stoichiometrical  numbers.  That 
this  should  be  absolutely  correct  in  the  case  of  those 
simple  bodies  which  have  been  most  accuratelj'  deter- 
mined, and  that  in  the  case  of  most  of  the  others  it 
should  accord  as  nearly  as  could  be  expected  for  difficult 
analyses,  is  certainly  not  to  be  looked  upon  as  an  accident, 
but  rather  it  is  to  be  assumed  that  the  numbers  of  all 
simple  bodies,  and  consequently  of  all  compound  sub- 
stances, form  integral  multiples  of  the  value  of  hj’drogen. 
There  are  also  deeper  theoretical  grounds  to  speak  for 


PROUT’S  VIEWS  AS  TO  MATTER.  27 

this.  This  combined  with  the  calculations  based  on 
volumes  furnish  the  chief  means  for  the  accurate  deter- 
mination of  these  chemical  magnitudes.” 

18.  Prout’s  Views  as  to  the  Constitution  of  flatter. 

— It  is  pertinent  to  the  subject  to  append  here  Prout’s 
views  as  to  the  constitution  of  matter. 

‘‘Although  we  have  thus  rendered  it  probable  that 
the  molecules  of  bodies,  considered  at  present  as  elemen- 
tary, are  immediately  compounded  of  many  others,  more 
or  less  resembling  them  ; yet  it  is  obvious  that  there 
must  be  a point  at  which  these  and  other  elements  exist 
in  a primary  and  ultimate  form,  and  beyond  which,  if 
the  elements  can  be  supposed  to  be  subdivided,  they 
must  become  something  altogether  different.  In  this 
respect,  therefore,  the  views  we  have  advanced  accord 
greatly  with  the  views  at  present  entertained,  and  the 
only  respect  in  which  our  views  differ  is  in  supposing 
that  the  self-repulsive  molecule  as  it  exists  in  the  gaseous 
form,  does  not  represent  the  ultimate  molecule,  but  is 
composed  of  many  sub-molecules.  With  respect  to  the 
nature  of  the  sub-molecules  of  these  bodies,  which  we  at 
present  consider  to  be  elements,  as  for  instance  of  0x3^- 
gen,  they  may  naturally  be  supposed  to  possess  the 
most  intense  properties.  Indeed  such  sub-mole- 
cules may  be  imagined  to  resemble  in  some  degree 
all  imponderable  matters,  heat,  etc.,  not  only  by  their 
extreme  tenuity,  but  in  other  characters  also  ; and  this 
very  intensity  of  property  and  character  may  be  reason- 
ably considered  as  one,  if  not  the  principal  reason,  why 


28 


THE  PERIODIC  LAW. 


they  are  incapable  of  existing  in  a detached  form. 

19.  Early  Numerical  Relations. — Leaving  now  the 
hypothesis  of  Prout,  let  us  consider  other  numerical 
relations  among  the  atomic  weights  than  their  divisi- 
bility by  some  common  factor. 

Before  the  atomic  theory  was  formulated  by  Dalton,  we 
have  Richter’s  table  of  equivalents  (in  1798)  exhibiting 
the  mass  relations  when  an  acid  is  neutralized  by  certain 
bases.  Richter  was  very  strongly  of  the  opinion  that 
his  constants  were  subject  to  special  laws,  particularly 
if  arranged  in  the  order  of  their  magnitude. 

Strictly  speaking,  the  first  notice  of  numerical  rela- 
tions existing  between  the  atomic  weights  of  the  elements, 
apart  from  the  question  of  their  being  multiples  of  the 
weight  of  hydrogen,  was  that  which  Prout  deduced 
from  his  table,  namely,  that  they  were  all  divisible  by 
four,  except  three,  which  were  divisible  by  two.  Of 
course,  Prout’s  table  was  very  crude  and  imperfect. 

20.  The  Triads  of  Dobereiner. — It  is  to  Dobereiner 
that  the  credit  is  due  for  drawing  attention  to  the 
first  striking  regularities.  • He  observed  the  fact  that 
certain  related  elements  occurred  in  threes,  the  cen- 
tral one  having  a mean  atomic  weight  and  mean 
properties  between  the  other  two.  These  were  called 
the  Dobereiner  Triads.  The  first  publication  con- 
cerning them  did  not  come  from  Professor  Dobe- 
reiner himself,  but  from  a letter  of  Professor  Wur- 
zer’s,  describing  the  work  of  Dobereiner  at  Jena  (5). 
He  says  that  Dobereiner,  working  upon  celestite,  found 


dobereiner’s  resume:  of  his  law.  29 

the  stoichiometrical  value  of  strontium  to  be  50.  This 
is  the  mean  of  calcium,  27.5,  and  barium  72.5,  (the  then 
accepted  atomic  weights).  Hence,  for  a moment,  he 
questions  the  independent  existence  of  strontium.  Still 
more  remarkable  is  the  fact  that  the  specific  gravity  of 
strontium  sulphate  is  the  mean  of  calcium  sulphate  and 
barium  sulphate.  He  was  led  to  believe  celestite  to  be 
a mixture  of  anhydrite  and  heavy  spar. 

A little  later  (6)  Dobereiner  published  a brief  paper 
bearing  upon  this  subject.  In  it  he  says  : 

Noteworthy  relations  are  revealed  when  one  examines 
the  stoichiometrical  values  of  the  chemical  elements  and 
compounds  arranged  in  series. 

1 . Those  most  often  found  in  plants  have  the  smallest 
values  and  are  the  most  abundant.  The  highest  values 
are  less  widely  distributed. 

2.  Those  corresponding  in  many  physical  and  chemi- 
cal properties,  as  iron,  cobalt  and  nickel,  have  almost 
the  same  stoichiometrical  value. 

3.  Compounds  which  have  like  equivalent  numbers 
are  also  most  alike  in  chemical  constitution. 

21.  Dobereiner’s  Resume  of  His  Law. — For  nearly 
a decade  there  is  silence  upon  this  subject.  Dobe- 
reiner’s  next  publication  seems  to  have  been  called 
forth  by  the  new  and  accurate  atomic  weight  determina- 
tions of  Berzelius  in  1825.  He  writes  (7)  of  his  having 
prophesied  in  his  lectures  that  perhaps  the  atomic  weight 
of  bromine  would  be  the  arithmetical  mean  of  those  of 
chlorine  and  iodine  and  rejoices  in  the  confirmation  of 


30 


THE  PERIODIC  DAW. 


this  by  the  determination  of  Berzelius.  Bromine  had 
just  been  discovered.  He  had  also  twelve  years  earlier 
placed  strontium  as  very  nearly  the  arithmetical  mean 
between  calcium  and  barium,  and  sodium  between 
lithium  and  potassium.  For  the  group  of  phosphorus 
and  arsenic  the  middle  factor  is  lacking.  If  sulphur, 
selenium  and  tellurium  belong  together,  which  is  to  be 
assumed  from  the  fact  that  the  specific  gravity  of  selen- 
ium is  the  mean  of  the  specific  gravities  of  sulphur  and 
tellurium,  then  selenium  is  the  mean  factor  in  the  mat- 
ter of  atomic  weights. 

Fluorine,  he  says,  does  not  belong  to  the  same  group 
of  salt-formers  as  chlorine,  etc.,  but  doubtless  to  one 
which  bears  the  same  relation  to  this  group  as  the  alka- 
lies to  the  alkaline  earths.  He  further  attempts  to  show 
in  this  grouping  the  intensity  of  the  chemical  attraction. 
Hydrogen,  oxygen,  nitrogen  and  carbon,  he  says,  seem 
to  be  isolated,  and  the  fact  that  nitrogen  is  the  mean 
between  oxygen  and  carbon  cannot  be  considered  as 
meaning  anything  since  no  analogy  exists  between  these 
elements. 

The  third  member  is  lacking  between  boron  and  sili- 
con, beryllium  and  aluminium,  yttrium  and  cerium. 
Magnesium  stands  quite  alone.  Iron  and  manganese  have 
chromium  as  their  middle  factor.  Other  possible  groups 
are  mentioned,  but  he  hesitates  to  express  his  opinion 
regarding  several  where  the  properties  are  poorty  deter- 
mined and  the  analogies  indistinct. 

The  important  fact  is  that  he  recognized  it  as  a law  of 
nature  that  the  elements  occurred  in  groups  of  threes, 


BERZELIUS  ON  SUCH  NUMERICAL  RELATIONS.  3 1 

the  middle  factor  being  the  arithmetical  mean  of  the 
other  two  in  atomic  weight  and  in  properties. 

22.  The  Slow  Extension  of  these  Views. — This  idea 
was  taken  up  by  other  chemists  who  tried,  as  the 
knowledge  of  the  elements  increased,  to  complete 
the  unfinished  triads  and  to  observe  other  analogies. 
These  triads  played  quite  an  important  part  in  Gmelin’s 
Hand  Book  of  Chemistry , the  most  influential  text-book 
of  chemistry  during  the  second  quarter  of  this  centurjr. 
With  this  exception  not  much  notice  was  taken  of  them. 

23.  Berzelius  on  Such  Numerical  Relations.  — In 

1845,  Berzelius  writes  (g.b):  “On  examining  the 

tables  of  atomic  weights  it  will  be  found  that  many 
bodies  have  an  equal  or  almost  equal  atomic  weight,  as 
for  instance,  chromium  and  iron,  nickel  and  cobalt; 
platinum  and  iridium  ; gold  and  osmium  ; many  have 
also  a weight  twice  as  large  as  the  others,  for  instance, 
silicon  and  boron  ; tungsten  and  molybdenum  ; magne- 
sium and  lithium,  etc.,  the  atomic  weights  of  oxygen 
and  sulphur,  selenium  and  tellurium  are  in  the  ratio  of  1, 
2,  5 and  8 ; add  to  this  those  which  seem  to  be  multi- 
ples of  the  equivalent  of  hydrogen  ; thus  it  is  seen  that 
between  bodies  of  a certain  similarity  of  properties,  cer- 
tain weight  relations  obtain.  It  could  easily  happen 
that  a revision  of  these  numbers  would  separate  them 
further  from  one  another  or  from  their  seeming  relations, 
and  it  is  therefore  useless  at  present  to  speculate  upon 
such  relations.  They  could  easily  lead  to  false  assump- 
tions.” 


CHAPTER  II. 

DUMAS  AND  THE  PERIOD  FROM  1850  TO  i860. 

24.  Slow  Development  of  the  Triads.  — For  more 
than  twenty  years  little  was  added  to  the  work  of 
Dobereiner  and  no  new  ideas  were  developed.  This 
was  in  part  due  to  imperfections  in  the  determinations  of 
the  atomic  weights  and  ignorance  as  to  whether  they 
should  be  written  as  had  been  done  by  Berzelius,  or 
many  of  them  doubled  as  was  done  by  Gerhardt. 

Further,  the  whole  question  of  atomic  weights  was  in 
much  doubt  and  numerical  speculations  concerning 
them  would  have  had  little  meaning  during  this  period. 
The  first  high  wave  of  hope  and  expectancy  following 
upon  the  introduction  of  the  idea  of  atoms  and  the  tables 
of  their  weights  was  succeeded  by  a corresponding 
period  of  doubt  and  difficulty.  Graham  made  no  dis- 
tinction between  the  atomic  weights  of  Dalton  and  the 
equivalents  of  Wollaston,  and  much  later  Laurent  devotes 
several  pages  to  discussing  the  merits  of  the  various  terms  : 
equivalents,  proportional  numbers,  and  atomic  weights. 

25.  Dumas’  Address  before  the  British  Association. 
— The  first  to  take  up  once  more  the  dropped  thread  was 
Dumas  (16).  He  had  devoted  his  chief  energies  to  atomic 
weight  determinations  and  had  erected  a lasting  monu- 
ment to  himself  in  his  determination  of  the  atomic 
weights  of  carbon  and  the  ratio  of  hydrogen  and  oxygen 
in  water,  besides  a number  of  other  determinations.  In 
1851  he  delivered  a lecture  before  the  British  Associa- 
tion at  Ipswich,  which  aroused  the  greatest  interest 


34 


THE  PERIODIC  LAW. 


among  chemists,  and  with  this  lecture  began  the  most 
prolific  decade  in  this  style  of  research  down  to  the  present. 

This  address  of  Dumas’  was  made  without  notes  and 
the  reports  of  it  lack  completeness.  It  seems  to  have 
been  drawn  out  in  a discussion  following  a report  pre- 
sented by  Faraday.  The  larger  portion  of  it  was  gath- 
ered together  with  some  later  papers  of  his  and  appeared 
in  a connected  form  in  1859.  In  this  address  he  drew 
attention  to  the  triads  of  Dobereiner,  wdthout,  how- 
ever, mentioning  this  author’s  name,  and  suggested 
that  in  a series  of  bodies,  if  the  extremes  are  known, 
then  by  some  law  the  intermediate  bodies  might  be 
discovered,  and  said  that  a suspicion  arose  as  to 
the  possibility  of  the  intermediate  body  being  com- 
posed of  the  extremes  of  the  series  and  thus  processes  of 
transmutation  might  be  hoped  for.  In  so  far  as  con- 
cerned the  composite  nature  of  the  intermediate  ele- 
ments he  but  reiterated  the  early  suspicion  of  Dobe- 
reiner.  He  then  alluded  to  the  possibility  that  such 
metals  as  were  similar  in  their  relations  and  could  be 
substituted  one  for  the  other  in  certain  compounds, 
might  also  be  found  transmutable  one  into  the  other. 
Dumas  spoke  of  the  idea  of  the  ancients  as  to  the  trans- 
mutation of  metals  and  their  desire  to  change  lead  into 
silver  and  mercury  into  gold  ; but  these  metals  do  not 
appear  to  have  the  requisite  similar  relations  to  render 
these  changes  possible.  He  then  passed  to  the  changes 
of  other  bodies,  such  as  the  transmutation  of  the  dia- 
mond into  black  lead  under  the  voltaic  arc,  etc. 

After  elaborate  reasoning  and  offering  many  analogies 


FARADAY’S  VIEWS. 


35 


from  his  stores  of  knowledge  as  to  chemical  analysis 
and  reactions,  Dumas  expressed  the  opinion  that  the 
law  of  the  substitution  of  one  body  for  another  in  groups 
of  compounds  might  lead  to  the  transformation  of  one 
group  into  another  at  will  ; and  that  we  should  endeavor 
to  devise  means  to  divide  the  molecules  of  one  body  of 
one  of  these  groups  into  two  parts,  and  also  the  molecules 
of  a third  body,  and  then  unite  them,  and  probably  the 
intermediate  body  might  be  the  result. 

The  facts  of  associated  occurrence  in  nature  of  such 
bodies  as  cobalt  and  nickel,  chlorine,  bromine  and 
iodine  were  taken  as  possible  evidence  in  favor  of  trans- 
mutation. 

2 6.  The  Effect  of  Dumas’  Address. — These  views  of 
Dumas  led  to  a number  of  experiments  by  Despretz,  and 
a lively  discussion  between  these  two  chemists  some 
years  later.  This  will  be  referred  to  at  the  proper  time. 
A more  immediate  result  followed  his  taking  up  of  the 
triads  of  Dobereitier  and  pointing  out  additional  regu- 
larities of  that  kind.  This  was  a fruitful  field  and  a 
strangely  fascinating  one  to  a man  who  once  enters  upon 
it.  In  the  next  few  years  we  have  a number  of  well- 
known  chemists  engaged  upon  this  work. 

27.  Faraday’s  Views. — It  is  perhaps  well  to  show7  by 
a quotation  from  Faraday  (20)  how  this  conservative  and 
distinguished  worker  looked  upon  the  opinions  advanced 
by  Dumas.  In  his  lecture  upon  chlorine,  bromine  and 
iodine  (pp.  158,  159,  160),  he  says  : 

When  we  come  to  examine  the  combining  pow7ers  of 


36 


THE  PERIODIC  DAW. 


the  three,  as  indicated  by  their  respective  equivalents  or 
atomic  weights  the  same  mutual  relation  will  be  ren- 
dered evident.  This  circumstance  has  been  made  the 
basis  of  some  beautiful  speculations  by  M.  Dumas — 
speculations  which  have  scarcely  yet  assumed  the  con- 
sistence of  a theory,  and  which  are  only  at  the  present 
time  to  be  ranged  among  the  poetic  day  dreams  of  a 
philosopher  : to  be  regarded  as  some  of  the  poetic  illum- 
inations of  the  mental  horizon,  which  possibly  may  be 
the  harbinger  of  a new  law.” 

He  then  considers  the  triads  of  salt-makers,  of  alka- 
lies, of  alkaline  earths,  and  the  sulphur  triad,  and  con- 
tinues : “ Thus  we  have  here  one  of  the  many  scientific 
developments  of  late  origin,  which  tend  to  lead  us  back 
into  speculations  analogous  with  those  of  the  alchemists. 
Already  have  we  seen  that  it  is  possible  for  one  body  to 
assume,  without  combination,  two  distinct  phases  of 
manifestation,  therefore  such  of  the  so-called  elements  as 
are  subject  to  allotropism,  are  not  the  unchanging  enti- 
ties they  were  once  assumed  to  be  ; and  now  we  find, 
after  our  attention  has  been  led  in  the  direction,  that  the 
triad  of  chlorine,  bromine,  and  iodine  not  only  offers  a 
well-marked  progression  of  certain  chemical  manifesta- 
tions, but  that  the  same  progression  is  accordant  with 
the  numerical  exponents  of  their  combining  weights. 
We  seem  here  to  have  the  dawning  of  a new  light,  in- 
dicative of  the  mutual  convertibility  of  certain  groups  of 
elements,  although  under  conditions  which  as  yet  are 
hidden  from  our  scrutiny.” 


THE  TRIADS  OF  KREMERS. 


37 


28.  The  Ascending  Series  of  Kremers. — One  of  the 

first  to  follow  in  the  footsteps  of  Dumas  was  Kremers 
(18)  who  pointed  out  the  existence  of  certain  regu- 
larly ascending  series  among  the  elements.  Thus,  when 
we  take  certain  analogous  non-metals  as  0 = 8 ; S = 16; 
Ti=  24.12;  P = 32;  Se  = 39.62,  etc.,  we  see  that  there 
is  a regular  difference  of  eight  between  them.  Now 
many  metals  lie  in  between  these  as  Mg=  12.07  between 
O and  S;  Ca=  20  between  SandTi;  Fe  = 28  between 
Ti  and  P,  etc.  Divide  these  by  four  and  the  non-metals 
give  an  even  number  and  the  metals  an  uneven.  A 
fundamental  element  with  the  atomic  weight  four  can 
therefore  be  assumed.  This  multiplied  by  an  even  num- 
ber gives  a non-metal,  by  an  uneven  it  gives  a metal. 
In  salts,  then,  looked  at  from  a dualistic  point  of  view, 
the  acid  is  an  even  multiple  of  four  and  the  base  is  an 
uneven  one,  and  this,  in  the  opinion  of  the  author,  lends 
strength  to  his  hypothesis  of  the  fundamental  element. 
Kremers  gives  a table  of  these  non-metals,  their  atomic 
weights,  and  their  factors  (multiples  of  4)  and  also  the 
metals  falling  in  the  intermediate  spaces.  To  this  latter 
fact  he  seems  to  attach  a good  deal  of  importance.  He 
includes  among  his  non-metals  several  bodies  now  re- 
garded as  metals. 

39.  The  Triads  of  Kremers. — In  later  communications 
(29),  he  follows  up  the  old  idea  of  triads  and  of  the 
probable  composite  nature  of  the  intermediate  elements. 
From  his  examination  of  various  compounds  he  de- 
duces the  law  : “If  two  different  bodies  mix  and  form  a 


38 


THE  PERIODIC  LAW. 


homogeneous  whole  the  intensity  of  the  physical  pro- 
perties of  these  mixtures  is  as  a rule  modified.” 

By  this  he  means  that  instead  of  the  product  having 
exactly  intermediate  properties,  these  properties  are 
modified  at  all  temperatures  save  one.  For  instance,  in 
examining  the  question  whether  the  solubility  of  the 
salts  of  the  intermediate  member  of  a triad  form  the 
means  of  the  solubilities  of  those  of  the  extremes,  he 
finds  this  to  be  true  for  a certain  definite  temperature 
only.  He  was  of  the  opinion  that  the  differences  ob- 
served in  the  atomic  weights  of  middle  members  of  triads 
from  the  calculated  were  due  to  the  temperature  at 
which  the  determinations  were  made,  and  that  only  at 
one  temperature  could  exactly  agreeing  compounds  be 
obtained. 

From  the  consideration  of  compounds  this  law  is 
transferred  to  elements,  and  he  examines  a number  of 
the  properties  in  connection  with  the  triads.  This  was 
an  attempt  at  placing  the  doctrine  of  triads  upon  a firm 
experimental  basis,  if  such  a thing  were  possible. 
Dobereiner  had  suggested  it  as  holding  good  for  some 
elements,  but  did  not  know  whether  it  could  be  ex- 
tended to  all.  It  had  been  extended  to  manj^,  but  there 
were  still  a number  of  doubtful  ones.  Kremers  united 
some  of  the  triads  into  what  he  called  conjugated  triads. 
His  study  of  the  properties  led  him  to  doubt  the  con- 
stancy of  the  atomic  weights. 

His  theory  of  conjugated  triads  may  be  explained  a 
little  more  in  detail.  One  of  these  ran  in  this  way  : 


GLADSTONE’S  ARRANGEMENT. 


39 


Li  = 7. 

Mg  = 24, 
Ca  = 4Q, 


Na=  23, 

Zn  = 40,  C 

Sr=  87.5,  Ba  = 


Ba=  137. 


In  these  triads  we  have  the  following  proportions  : 
Li  : Na  : K as  7 : 23  : 39  as  Li  : Mg  : Ca. 

This  close  agreement  is  not  found  in  every  case,  how- 
ever. It  was  claimed  that  there  were  eight  of  these  con- 
jugated triads,  and  each  twenty-seven  elements  can  be 
arranged  in  space  in  the  form  of  a cube.  Of  these  cubes 
there  are  again  three  or  a triad ; one  positive,  one  nega- 
tive and  one  intermediate.  The  number  of  the  possible 
elements  is  then  a power  of  three,  probably  three  raised 
to  the  fourth  power. 

Kremers  at  first  thought  that  this  cubic  triad  repre- 
sented the  natural  arrangement  of  the  elements.  This 
view  he  gave  up  later  (1863),  and  with  it  the  doctrine 
of  the  triads  in  the  strict  sense. 

30.  Gladstone’s  Arrangement  in  the  Order  of  their 
Atomic  Weights. — In  1853  Gladstone  (21)  published 
an  article  on  the  relation  between  the  atomic  weights  of 
analogous  elements.  In  this  he  arranged  the  elements 
in  the  order  of  their  atomic  weights,  using  the  numbers 
given  in  Liebig’s  Jahresberichte  for  1851.  A few  years 
later  this  method  of  arranging  them  brought  out  the 
main  features  of  the  natural  law,  but  the  numbers  used 
by  Gladstone  are  too  faulty  to  show  any  noteworthy 
regularity.  Still  it  is  interesting  to  note  that  he  is  the 
first  to  arrange  them  in  this  order.  He  observed  noth- 
ing striking  in  these  numbers  except  the  number  of 


40 


THE  PERIODIC  LAW. 


them  congregated  around  28  and  52,  and  that  there  was 
only  one  between  80  and  99,  and  then  followed  a group 
of  four. 

Prof.  DeMorgan helped  him  to  calculate  the  probability 
of  such  occurrence  being  accidental,  and  found  that  the 
odds  were  250  to  one  against  the  same  number  occurring 
six  times  in  the  sixty  elements.  Taking  the  elements 
next  by  groups,  as  given  in  Gmelin’s  Handbook,  Glad- 
stone found  the  numerical  relations  to  be  of  three  kinds. 

1 . The  atomic  weights  of  analogous  elements  are  the 
same. 

2.  The  atomic  weights  of  analogous  elements  are  in 
multiple  proportions. 

3.  The  atomic  weights  of  analogous  elements  may 
differ  by  certain  regular  increments. 

In  the  first  class  fall  Cr,  Mn,  Fe,  Co,  Ni  with  atomic 
weights  approximating  28 ; Pd,  Rh,  and  Ru  approxi- 
mating 52  : and  Pt,  Ir,  and  Os  approximating  99. 

In  the  second  class  we  see  the  platinum  group  double 
the  palladium  group,  and  gold  double  platinum.  Again 
he  gives  0 = 8 and  S = 16 ; and  B = 10.9  and  Si  = 21.3 
as  examples.  A group  consisting  of  Ti,  Mo,  Sn,  V,  W, 
and  Ta  is  cited  as  having  atomic  weights  which  are  all 
multiples  of  1 1.5. 

In  the  third  class  we  have  elements  with  intermediate 
properties  occupying  intermediate  positions.  Li,  6.5  ; 
Na,  23  ; K,  39.2. 

The  first  kind  of  analogy  he  compared  with  allotropism 
if  that  were  carried  out  through  all  the  compounds  of  an 
element. 


HOMOLOGOUS  SERIES  OF  COOKE.  4 1 

The  second  is  to  be  compared  with  polymerism  in  or- 
ganic chemistry. 

The  third  is  analogous  to  the  homologous  series  in  , 
organic  chemistry. 

He  regarded  the  doctrine  of  triads  as  to  some  extent  a 
natural  law,  but  the  existence  of  these  triads  was  to  him 
an  unsolved  problem. 

31.  The  Homologous  Series  of  Cooke. — In  the  follow- 
ing year  Professor  Josiah  P.  Cooke  (22)  published  a very 
detailed  study  of  these  numerical  relations.  He  thought 
that  the  doctrine  of  triads  as  given  by  Dumas  was  only  a 
partial  view  of  the  subject,  since  these  triads  are  only 
parts  of  series  similar  in  all  respects  to  the  homologous 
series  of  organic  chemistry,  in  which  the  differences  be- 
tween the  atomic  weights  is  a multiple  of  some  whole 
number.  In  so  far  as  he  pointed  out  that  these  triads 
broke  up  natural  groups  of  elements,  he  struck  a fatal 
blow  to  the  doctrine  of  triads. 

All  the  elements,  he  said,  may  be  classified  into  six 
series,  in  each  of  which  the  number  whose  multiples 
form  the  differences  is  different  and  may  be  said  to 
characterize  the  series.  In  the  first  it  is  nine,  in  the 
second,  eight,  in  the  third,  six,  in  the  fourth,  five,  in  the 
fifth,  four,  and  in  the  last,  three.  The  elements  are  fur- 
ther arranged  in  series  according  to  the  strength  of  their 
electro-negative  properties,  or  in  other  words,  as  their 
affinities  for  oxygen,  chlorine,  sulphur,  etc.,  increased, 
while  those  for  hydrogen  decrease,  as  we  descend.  He 
found  the  difficulty  with  most  of  the  classifications,  exist- 


42 


THE  PERIODIC  LAW. 


ing  at  that  time,  to  be  that  they  were  too  one-sided,  based 
upon  one  set  of  properties  to  the  exclusion  of  others.  If 
there  were  any  fundamental  property  common  to  all 
elements,  the  law  of  whose  variation  was  known,  this 
might  serve  as  the  basis  of  a correct  classification.  Pro- 
fessor Cooke  laid  special  stress  upon  the  correspondence 
of  his  grouping  with  the  homologous  series  of  organic 
chertiistry. 

The  elements  of  any  one  of  the  six  series  form  similar 
compounds  and  produce  similar  reactions ; moreover 
they  resemble  each  other  in  another  respect  in  which 
the  members  of  the  organic  series  do  not,  their  crystal- 
line forms  are  the  same,  or,  in  other  words,  they  are 
isomorphous.  As  one  general  symbol  will  express  the 
composition  of  the  whole  organic  series,  so  a simple 
algebraic  formula  will  express  the  atomic  weight,  or,  if 
you  may  please  so  to  term  it,  the  constitution  of  a series 
of  elements. 

In  the  first  series  the  atomic  weights  gradually  in- 
crease from  oxygen  downward  and  admit  of  a general 
expression,  which  is  8 — |—  nq.  This  series  is  comparable 
to  the  formic  acid  series.  For  the  next  series  the  generic 
formulas  are  8 — |—  ?z8  and  4 -f-  n8.  Thus  this  series  is 
divided  into  two  sub-series,  in  which  there  are  marked 
analogies.  There  seems  to  be  no  proof  of  isomorphism 
between  the  sub-series. 

For  the  next  or  six-group  the  formula  is  16  -|-  m2. 
Oxygen  is  placed  at  the  head  of  each  one  of  these  three 
groups  because  ‘ 1 its  atomic  weight  seemed  to  be  the 
nucleus  of  all  three.”  In  other  cases  also  we  find  the 


COMPOUND  NATURE  OF  THE  ELEMENTS.  43 

same  element  occurring  in  more  than  one  group.  The 
five-series  is  the  shortest  of  them  all,  containing  only 
three  elements.  Its  formula  is  6 — |—  225.  The  four-series 
is  much  the  largest  of  all,  containing  what  are  known  as 
the  heavy  metals.  This  is  divided  into  two  sub-series 
with  the  two  formulas  4+  224  and  2 -j-  724.  The  three- 
series  and  last  is  composed  of  hydrogen  and  the  alkalies, 
only  three  of  which  were  known  at  that  time.  The  for- 
mula here  is  1 + 223. 

Cooke  caught  a glimpse  of  one  great  truth,  and  that 
was  that  we  must  not  merely  separate  out  here  and  there 
so-called  related  elements,  but  must  grasp  the  fact  that 
there  is  a relationship  even  between  the  apparently  dis- 
similar. He  says  that  one  of  the  most  remarkable  facts 
brought  out  by  his  system  of  tabulation  is  the  “affilia- 
tion of  the  series.”  “Many  of  the  elements,  while  they 
manifestly  belong  to  one  series,  have  properties  which 
ally  them  to  another.”  He  concludes,  that  this  table 
shows  that  the  chemical  elements  may  be  classified  in  a 
few  series  similar  to  the  series  of  homologues  of  organic 
chemistry ; secondly,  that  in  these  series  the  properties 
of  the  elements  follow  a law  of  progression ; and  finally 
that  the  atomic  weights  vary  according  to  a similar  law, 
which  may  be  expressed  by  a simple  algebraic  for- 
mula. 

32.  Kotikovsky  and  the  Compound  Nature  of  the  Ele= 
ments.  — In  this  same  year  (1854) , Kotikovsky  (23) 
took  up  the  idea  of  the  compound  nature  of  the  elements 
suggested  by  Dumas,  and  attempted  to  prove  the  truth 


44 


THE  PERIODIC  LAW. 


of  this  by  a singular  mode  of  reasoning  and  without  ex- 
perimental proofs.  It  has  not  been  possible  to  get  at 
the  original  article,  nor  has  it  been  deemed  necessary  to 
make  a very  extended  search  for  it.  Following  the  lead 
of  Priestley  and  the  phlogistic  chemists,  he  assumed 
the  presence  of  hydrogen  in  all  combustible  bodies.  He 
develops  a simple  appearing  system  of  chemistry  in 
which  there  are  no  troublesome  exceptions  to  his  rules, 
because  all  facts  which  do  form  exceptions  are  stated 
otherwise  and  made  to  accord.  He  gives  no  proof  of 
how  he  found  these  to  be  different  from  what  is  com- 
monly accepted.  The  following  example  of  his  mode  of 
reasoning  will  suffice:  “Waters  1 8 can  not  contain 

oxygen  = 32  because  no  part  can  weigh  more  than  the 
whole.” 

33.  Low’s  Theory  as  to  the  Composition  of  the  Ele= 
ments.  — Low  (25)  held  that  hydrogen  and  carbon 
were  the  original  constituents  of  many  of  the  elements. 
Thus  he  regarded  N as  C2H2  and  O as  CHH,  etc.  As 
experimental  evidence  he  offered  the  fact  that  potas- 
sium or  sodium  melted  under  rock-oil  became  oxidized, 
and  this  he  regarded  as  a making  of  oxygen. 

Since  hydrogen  and  carbon  (atomic  weight  6)  had  at 
that  time  lower  atomic  weights  assigned  them  than  any 
other  elements,  and  since  they  were  capable  beyond  all 
the  others  of  entering  into  combination  with  one  another, 
he  assumed  that  all  elements  are  composed  of  the  two. 
Or,  to  state  the  proposition  more  generally,  all  bodies 
may  be  derived  from  hydrogen  and  carbon  or  from  the 


COMPOSITION  OP  THP  ELEMENTS.  45 

principles,  elements,  or  matter,  of  which  hydrogen  and 
carbon  are  themselves  formed. 

He  examined  in  detail  the  various  elements  and  en- 
deavored by  appeal  to  experiments  and  analogies  to  show 
how  they  were  made  up  of  one  another  and  all  composed 
of  hydrogen  and  carbon.  The  relations  existing  among 
organic  substances  were  adduced  in  support  of  the  theory. 

Further,  he  criticised  the  reasons  for  holding  certain 
bodies  to  be  elementary  and  a demonstration  was  given  of 
how  all  elements  might  be  built  up  of,  say,  two  bodies, 
A and  B.  Of  the  nature  of  the  ultimate  atoms  or  parti- 
cles we  “know  and  can  know  nothing.”  “We  infer 
that  they  have  weight  and  extension.”  “We  cannot 
conceive  a body  to  have  weight  and  extension,  and  the 
parts  of  which  it  is  formed  to  be  destitute  of  weight  and 
extension,  however  far  we  suppose  the  division  to  be  car- 
ried.” The  conception  of  Boscovich  of  the  atom  as  in- 
finitesimally small  and  hence  a mathematical  point,  or 
of  the  philosopher  as  merely  a resisting  point,  and  hence 
all  matter  to  be  but  a system  of  forces  is  not  the  idea  of 
the  chemist  who  regards  it  as  a “ particle  of  matter.” 

Low  believed  that  it  was  unjust  to  regard  bodies  as 
simple  or  elementary  merely  because  we  are  unable  to  de- 
compose them  by  the  means  at  our  disposal.  Induction 
and  analogy  should  be  relied  upon  as  well  as  experi- 
ment. Without  them  experiment  would  fail  to  conduct 
us  to  the  discovery  of  natural  laws.  “It  would  be  justice 
to  regard  a body  as  compound  when  we  are  not  able  to 
prove  it  to  be  simple.”  Many  things  show  that  the  two 
arbitrary  classes,  elements  and  compounds,  are  not  to  be 


46 


THE  PERIODIC  LAW. 


divided  by  so  wide  a chasm  as  a “ distinct  corpuscular 
constitution.” 

‘‘Davy,  in  the  early  period  of  his  chemical  inquiries, 
was  conducted  to  the  opinion  that  sulphur  and  phos- 
phorus, which  give  off  hydrogen  under  the  influence  of 
voltaic  action,  might  be  compound.  He  even  expressed 
the  opinion,  that  all  simple  bodies  might  be  compound 
and  resoluable  into  hydrogen  and  some  unknown  base. 
He  never,  however,  pursued  his  own  hypothesis  to  its 
consequences,  and  at  length  he  seems  to  have  abandoned 
it  altogether.” 

34.  The  Extension  of  the  Triads  by  Lennsen. — L,enn- 
sen,  in  1857,  (26)  returned  to  the  doctrine  of  the  triads 
and  is  almost  the  last  one  to  attempt  the  development  of 
this  line  of  speculation.  He  endeavored  to  extend  the 
triads  to  all  of  the  elements,  grouping  them  by  their 
physical  and  chemical  characteristics.  He  formed,  in 
all,  twenty  triads,  thus  including  the  sixty  best  known  ele- 
ments. Mercury  formed  the  uniting  member,  appear- 
ing in  the  tenth  and  again  in  the  twentieth  triad.  The 
first  ten  triads  contained  the  non-metals  and  acid-form- 
ing metals  ; those  from  eleven  to  twenty  contained  the 
metals.  He  noted  a further  intimate  relationship  be- 
tween the  triads.  Thus,  for'  each  three  triads  we  have 
the  middle  members  forming  a new  triad,  and,  there- 
fore, the  three  triads  formed  what  he  called  an  enneade. 
This  is,  of  course,  a very  similar  idea  to  the  conjugated 
triads  of  Kremer’s.  He  saw,  however,  that  the  division 
into  triads  was  not  entirely  satisfactory.  The  middle 


HOMOLOGOUS  SERIES  OF  DUMAS. 


47 


member  did  not  always  present  in  every  respect  the  in- 
termediate characteristics.  He  then  suggested  a divi- 
sion into  diads  with  the  third  member  forming  a link  or 
binding  member.  The  triads,  K,  Na,  Li  ; Ba,  Sr,  Ca  ; 
Mg,  Zn,  Cd  ; became  diad  K,  Na,  and  link  Li  ; diad 
Ba,  Sr,  and  link  Ca  ; diad  Mg,  Zn,  and  link  Cd,  and  so 
on  for  the  others.  He  laid  especial  stress  upon  the 
analogous  salts  of  these  diads  crystallizing  with  the  same 
amount  of  water. 

Other  properties,  as  the  color  of  the  salts,  color  given 
to  flame,  etc.,  were  also  brought  to  bear  in  effecting  this 
division. 

35.  Elaboration  of  the  Homologous  Series  by  Dumas. 

— In  the  latter  part  of  the  year  1857,  Dumas  (27) 
took  up  again  the  subject  of  the  numerical  regularities 
of  the  atomic  weights  and  this  time  not  from  the  point 
of  view  of  the  triads  but  of  the  homologous  organic 
series.  He  made  use  of  the  formula  devised  by  Cooke, 
a -j-  nd.  The  facts  that  organic  radicals  are  not  always 
produced  by  addition  but  sometimes  by  substitution  and 
again  that  there  are  certain  series  of  radicals  where  the 
fundamental  molecule  itself  changes  as  well  as  the  bodies 
added  to  or  substituted  in  it,  are  especially  emphasized. 
In  comparing  the  equivalents  of  the  elements  he  noted 
that  the  halogens  do  not  form  a simple  progression. 
The  relation  between  their  equivalents  is,  however,  ex- 
hibited by  the  scheme  a,  a -j-  d,  a-\-2d-\-d' , 2 a -\-2d-\-  2d' . 
Thus  F — I9;C1=  19-j-  16.5;  Br=i9  + 2(i6.5)  + 28; 
1=  2(19)  -j-  2(16. 5)  -j-  2(28).  And  so  for  the  nitrogen 
group;  N=i4;  P=i4+i7;  As  = 14+ 17 +44 ; Sb= 


48 


THE  PERIODIC  LAW. 


14-)-  17  + 88;  Bi  = 14+  17  + 176.  Similar  series  are 
given  for  C,  B,  Si,  and  Zr  ; as  well  as  for  Sn,  Ti,  and 
Ta.  For  the  oxygen  group  we  have  the  series  a , 2a, 
5 a,  8a,  or  a,  a-\-d,  a-\-\d,  a-\~id.  Taking  the  latter 
as  preferable  from  analogy  , 0=8;  S = 8-f-8;  Se  = 
8+32;  Te  = 8 + 56.  A common  difference  of  eight 
also  connects  the  following  : Mg=  12;  Ca  = 12  -|-  8 ; 
Sr=i2+32;  Ba=  12  + 56;  Pb=24+8o.  The  fol- 
lowing have  a common  difference  of  sixteen  : Li  = 7 ; 
Na  = 7 — (—  16  ; K = 7 + 32.  Mo,  W,  Cr,  and  V form  a 
similar  series  with  the  difference  22. 

36.  Double  Parallelism  of  Dumas. — A few  months 
after  this  Dumas  brought  out  his  idea  of  double  paral- 
lelism. He  made  the  following  comparison  : 

N = 14  P = 3i  As=75  Sb=i22 

F = 19  Cl=  35.5  Br  = 80  I =127 

On  adding  108  to  the  number  for  nitrogen  we  get  that 
for  Sb,  and  on  adding  it  to  F we  get  I,  and  so  the  addi- 
tion of  61  gives  us  respectively  As  and  Br.  These  facts 
teach  the  propriety,  he  says,  of  arranging  the  metals  in 
series  that  shall  show  a double  parallelism,  for  such  a 
classification  brings  to  view  the  various  analogies  exist- 
ing between  these  elements.  In  fact,  when  arranged  by 
natural  families,  each  of  the  elements  is  in  proximity  to 
two  others,  belonging  to  two  related  families  ; and  these 
related  families  occupy  the  two  lines  next  to  that  con- 
taining the  metal  selected  for  comparison.  Finally  each 
metal  is  surrounded  in  such  a table  by  four  others,  which 
are  united  to  it  by  analogies  of  different  kinds  and  more 
or  less  close. 


COMPOSITION  OF  THE  ELEMENTS.  49 

37.  Dumas’  Views  as  to  Compound  Nature  of  the 
Elements. — In  a further  communication  he  draws  this 
comparison  between  the  elements  and  the  other 
bodies  in  nature.  The  compounds  which  the  three 
kingdoms  offer  for  our  study  are  reduced  by  analysis  to 
a certain  number  of  radicals  which  may  be  grouped  in 
families.  Secondly,  the  characters  of  these  families 
show  incontestable  analogies.  But  the  radicals  of  min- 
eral chemistry  differ  from  the  others  in  that  if  they  are 
compound  they  have  a stability  so  great  that  no  known 
forces  are  capable  of  producing  decomposition.  The 
analogy  authorizes  the  inquiry  whether  the  former  may 
not  be  compound  as  well  as  the  latter.  It  is  necessary 
to  add,  he  says,  that  the  analogy  gives  us  no  light  as  to 
the  means  of  causing  this  decomposition  and  if  it  is  ever 
to  be  realized  it  will  be  by  methods  or  forces  yet  unsus- 
pected. 

In  1859,  Dumas  (34)  collected  and  published  in  one 
article  the  more  important  parts  of  his  -work  upon  the 
numerical  relations  of  the  atomic  weights,  laying  special 
stress  upon  the  probably  composite  nature  of  the  ele- 
ments. 

38.  The  Dumas=Despretz  Controversy  as  to  the  Com- 
position of  the  Elements. — This  idea  of  the  composite 
nature  was  combatted  by  Despretz  (35),  who  per- 
formed a number  of  experiments  to  determine,  if  possi- 
ble, whether  the  elements  could  be  looked  upon  as  vary- 
ing modifications  or  condensations  of  one  and  the  same 
material  or  whether  they  were  compounds  of  unknown 
constituents.  For  instance,  he  found  that  copper  sul- 


50 


THE  PERIODIC  LAW. 


phate  gave  at  the  beginning  and  end  of  its  electrolysis 
the  same  body,  copper,  with  the  same  characteristics. 
So  too  by  fractional  precipitation  of  copper  with  hydro- 
gen sulphide  or  with  sodium  carbonate  he  got  only  one 
substance.  The  same  was  true  of  lead  nitrate  when 
fractionally  precipitated  by  means  of  sodium  carbonate. 
Electrodes  were  sunk  in  melted  lead  and  the  metal  ex- 
amined at  the  positive  and  negative  end.  Both  were 
identified  with  ordinary  lead.  Zinc, on  being  fractionally 
distilled,  yielded  zinc  only  and  the  same  was  true  of 
chlorine.  These  suffice  to  give  the  character  of  his  ex- 
periments. He  thought  he  could  conclude  that  the  ele- 
ments consisted  of  peculiar  elementary  material,  un- 
changeable in  its  nature  and  properties  and  that  they 
were  by  no  means  the  same  matter  in  different  molecular 
condition. 

Dumas  replied  that  Despretz’s  methods  were  inade- 
quate to  solve  this  question  and  that  no  just  conclusions 
could  be  drawn  from  them. 

Despretz  defended  the  correctness  of  his  researches. 
He  volatilized  Cu,  Bi,  and  Ag  in  a stream  of  hydrogen 
by  the  white  heat  of  a furnace  and  more  rapidly  by 
a strong  galvanic  current  and  showed  that  these  vol- 
atilized metals  gave  the  same  compounds  as  be- 
fore. He  also  showed  that  Fe,  Cu,  Bi,  and  Ag  gave  out 
no  hydrogen  nor  other  gas  at  a white  heat. 

It  does  seem  as  if  this  work  of  Despretz  was  one  of 
supererogation  as  Dumas  had  distinctly  stated  in  his 
speculations  upon  the  composite  nature  of  the  metals 
that  their  decomposition,  if  ever  accomplished,  would  be 


pettenkofer’s  group  differences.  51 

by  means  and  methods  yet  unsuspected.  Dumas’  reply 
to  such  criticism  as  these  was  a very  easy  one. 

39.  Pettenkofer’s  Group  Differences. — Pettenkofer 
(30),  in  pursuing  this  subject  of  the  regularities  in  the 
weights,  first  criticized  the  doctrine  of  triads.  That  the 
equivalent  of  a body,  he  says,  should  form  a mean  between 
two  very  similar  bodies  is  certainly  only  something  ac- 
cidental. One  can  compare  F,  Cl,  and  Br  as  well  as  Cl, 
Br,  and  I and  then  the  mean  relation  does  not  appear. 

He  maintains  that  a remarkable  relation  does  appear, 
however,  when  one  examines  the  numerical  differences 
between  certain  natural  groups  of  elements,  these  differ- 
ences seeming  to  be  nearly  multiples  of  one  and  the  same 
number.  He  examines  the  alkalies,  alkaline  earths, 
chromium  group,  and  sulphur  groups  and  finds  the  num- 
ber to  be  eight.  ThusLi=7  + 2X8  = Na+  2 X 8 = K. 
Another  number,  five,  is  found  for  the  halogens  and  for 
the  C,  B,  Si  group ; also  by  the  group  N,  P,  As,  andSb 
it  seems  to  be  made  up  of  5 and  8. 

He  regards  the  occurrence  of  these  differences  approx- 
imating eightastoo  frequent  to  be  accidental,  thus  making 
use  of  the  style  of  argument  which  he  had  rejected  in  the 
case  of  the  triads.  By  taking  eight  as  the  difference  and 
using  some  member  of  each  group  as  the  unit  he  calcu- 
lates out  the  atomic  weights  for  the  group.  A table  is 
given  in  which  the  atomic  weights  are  thus  calculated 
and  compared  with  the  observed  weights  and  the  differ- 
ences are  also  tabulated.  He  did  not  think  that  the  fact 
that  this  number  eight  was  the  one  then  regarded  as  the 
atomic  weight  of  oxygen  should  have  any  meaning. 


52 


THE  PERIODIC  LAW. 


40.  Comparison  of  Elements  withCompoundRadicals. 

— He  further  compared  the  elements  with  the  organic 
radicals  and  thought  that  the  metals  -would  come  to  be 
regarded  as  compound  radicals.  He  thought  the  whole 
matter  could  be  stated  briefly  thus  : 

1.  The  equivalents  of  the  inorganic  elements,  which 
form  natural  groups,  show  among  themselves  such 
constant  differences  as  the  equivalents  of  organic  com- 
pound radicals  which  belong  to  natural  groups. 

2.  The  simple  inorganic  elements  can  therefore  be  re- 
garded from  the  standpoint  of  the  compound  organic 
radicals. 

The  difference-numbers  are  not  always  the  same  number 
or  its  multiples  but  are  to  be  looked  upon  as  built  up  of 
two  numbers  and  their  multiples,  thus  the  18  of  the 
nitrogen  group  is  2 X 5 + 8. 

Pettenkofer  made  a claim  for  priority  that  he  had  de- 
livered a lecture  upon  these  difference-numbers  one  }rear 
before  Dumas’  brilliant  address.  More  work  was  needed 
upon  the  atomic  weights  to  enable  him  to  complete  his 
confirmation  of  the  supposed  law.  He  had  applied  to 
the  Royal  Society  of  Munich  for  aid  which  had  been 
denied  him  and  he  had  therefore  given  the  work  up. 
This  claim  was  justified  so  far  as  his  ideas  concerning 
difference-numbers  and  compound  radicals  were  con- 
cerned. The  trend  of  the  work,  however,  was  different, 
and  Pettenkofer’s  was  almost  unknown  while  the  influ- 
ence of  Dumas’  speculations  was  widely  felt. 

41.  Odling’s  Triads. — Odling  (28)  should  be  men- 


COMPARISON  WITH  ORGANIC  RADICALS. 


53 


tioned  as  another  of  the  followers  of  the  doctrine  of  triads. 
He  made  these  the  basis  of  a system  of  the  elements 
which  he  arranged  according  to  their  physical  and  chemi- 
cal characteristics,  into  natural  families.  In  several 
cases  he  included  more  than  one  triad  in  the  same  family. 
These  natural  groupings  of  the  elements  were  based  upon 
the  properties  of  the  elements  other  than  the  atomic 
weights  and  may  be  regarded  as  a development  of  the 
families  already  recognized.  For  this  all  properties  must 
be  considered.  Two  elements  forming  a large  number  of 
compounds  of  analogous  composition  with  marked  similar- 
ity of  properties  must  be  grouped  together.  If  a marked 
general  accordance  is  found  a discrepancy  in  some  parti- 
cular property  is  to  be  overlooked.  This  grouping  re- 
quires a careful  and  thorough  discussion  of  the  proper- 
ties as  far  as  they  are  known.  Such  a classification  is 
likely  to  be  upset  by  increased  knowledge  of  the  proper- 
ties. The  groups  are  mainly  triads  though  several  are 
larger.  The  intermediate  terms  of  the  triads  are  pos- 
sessed of  intermediate  atomic  weights  and  properties. 
The  mean  differences  or  increments  of  atomic  weights  in 
the  different  groups  were  noted.  He  spoke  of  the  larger 
groups  as  triads  with  which  were  associated  analogous 
elements  having  atomic  weights  approximately  one  half 
that  of  the  first  member  or  double  that  of  the  last  member 
of  the  triad.  Sometimes  there  occur  what  he  calls  twin 
elements. 

42.  Mercer’s  Comparison  with  the  Organic  Rad= 
icals. — Mercer  (31),  in  a paper  before  the  British  As- 
sociation, pointed  out  many  numerical  relations  and 


54 


THE  PERIODIC  LAW. 


differences  between  groups  of  elements.  He  carried  out 
more  fully  the  comparison  with  the  organic  radicals. 
In  the  alkaline  group,  Li  = 7 corresponds  to  H ; Na  = 23 
corresponds  to  C„H3 ; K = 39  corresponds  to  C4H.. 
He  made  use  of  some  of  the  difference-numbers  of 
Pettenkofer  and  also  noted  that  the  difference  between 
the  nitrogen  group  and  the  halogens  is  5 ; N = 14, 
F=i9,  &c.  Hence  F = 5+N;  Br—  5+ As.  Again 
42  = 0;  43  = Mg:  44  = S;  46=Ca;  4I0  = Se;  4„  = Sr ; 
4i6—  Te  ; 417  = Ba;  4+  3=Fi ; 46  + 3 = Na  ; 49  + 3=K- 
Let  us  take  as  a further  example  one  of  his  groups. 
C = 6 or  5+1  = 6 = ab+b=CH  + H. 

B = 5 + 6 = ii  or  52  -)-  1 = 2 ab+b  = 2CH+H=Methyl 
Si  = 53+  6=21  or  54+  1 = 4ab+  b = 4CH  + H = Ethyl 
Zr  = 56  + 6 = 3 1 or  56  + 1 = 6ab  + b =6CH+  H=  Propyl 
A number  of  such  groups  are  given.  There  is  ap- 
pended what  is  called  a table  of  the  Atomic  Parallels, 
which  is  the  first  attempt  at  representing  the  atomic 
weights  in  a diagram.  The  atomic  weights  form 
the  ordinates.  Then  the  oxygen  group  is  repre- 
sented by  three  straight  lines,  the  first  beginning 
at  8 and  ending  at  16,  the  second  beginning  at  six- 
teen and  going  to  40,  the  third  beginning  at  40  and 
going  to  64.  For  the  magnesium  group  these  lines  began 
at  12,  20,  44  respectively  and  ended  at  64.  The  foot 
notestates : “oxygen  and  magnesium  groups,  showing  the 
steps  or  differences  between  each  member;  they  are 
parallel  except  that  Mg  is  raised  up  4.  Similar  parallels 
are  given  for  the  nitrogen  and  chlorine  groups.”  From 
his  tables  of  the  groups  compared  with  the  organic 


REVISION  OF  THE  ATOMIC  WEIGHTS. 


55 


radicals  Mercer  deduced  a general  formula  as  an  expres- 
sion for  the  atomic  weights  of  single  groups  of  elements  ; 
as  mx  or  mx-\-y,  where  x and y are  constant  for  the  same 
group. 

4 3.  The  Revision  of  the  Atomic  Weights  by  Canniz- 
zaro.— In  i860  and  the  year  or  two  following,  M.  Carey 
Lea  published  a number  of  articles  bearing  upon 
the  numerical  relations  of  the  equivalents.  As  they 
were  continuations  of  the  same  general  search,  though 
in  a rather  scattering  fashion,  for  some  law  or  laws 
underlying  these  relations  they  will  be  mentioned  to- 
gether. Preliminary  to  this  mention,  however,  it  must 
be  stated  that  the  atomic  weights  were  now  in  a much 
more  satisfactory  condition.  As  has  been  seen  from  the 
quotations  already  made  from  various  workers,  there 
was  very  little  uniformity  in  the  usage  as  regards  these 
numbers.  Some  took  one  authority,  some  another,  and 
the  numbers  differed  widely  and  were  quite  far  removed 
in  many  cases  from  those  at  present  in  use.  So  great 
was  this  confusion  and  discord  that  a meeting,  inter- 
national in  character,  was  called  in  i860  to  meet  at 
Karlsruhe  to  come  to  some  agreement  with  regard  to 
their  definite  and  fixed  representation.  The  unitary 
theory  represented  by  Cannizzaro  gained  much  ground 
yet  it  was  evident  that  no  full  agreement  could  be  arrived 
at. 

Cannizzaro’s  views  afterwards  prevailed.  They  were 
based  on  the  conceptions  of  Avogadro,  Gerhardt  and 
Regnault  and  withstood  all  criticism.  Hk  idea  of  atoms 
was  the  smallest  portion  of  an  element  which  enters  into 


56 


THE  PERIODIC  LAW. 


a molecule  of  its  compounds  and  his  table  of  the  atomic 
weights  was  the  first  that  gave  such  approximately  cor- 
rect values  as  admitted  of  an  insight  into  the  underlying 
laws. 

44.  Lea  uses  the  Atomic  Weight  Differences. — Lea 

began  his  first  paper  with  the  remark  (39):  “Increas- 
ing accuracy  in  the  determination  of  the  chemical 
equivalents  of  the  simple  bodies  seems,  to  destroy  more 
and  more  the  numerical  relations  once  supposed  to  exist 
between  the  equivalent  numbers  of  certain  series  of 
elements  nearly  related  to  each  other  by  their  properties. 
Yet  it  can  be  demonstrated  that  such  relations  exist.” 
The  first  part  of  Lea’s  work  referred  to  the  numerical 
differences  between  the  atomic  weights  of  the  elements 
of  the  same  group  or  family.  Thus  he  formed  a descend- 
ing series  begining  with  Sb  120  and  having  a regular  de- 
crease of  45.  In  this  way  he  hit  very  nearly  the  atomic 
weights  of  the  other  elements  of  the  group.  But  he  did 
not  stop  there  going  on  to  a number  of  negative  equiva- 
lents and  remarking  upon  the  cases  where  they  happened 
to  coincide  with  known  positive  atomic  weights.  He 
found  the  difference  between  the  elements  of  the  mercury 
group  and  so  also  for  the  magnesium  group.  The 
difference  45  is  found  between  the  two  groups  of  the 
platinum  metals.  Between  a number  of  elements,  not 
easily  classed  together,  he  observed  that  the  difference 
was  nearly  twice  44.  And  so  for  certain  acid-forming  ele- 
ments, as  Sn,  Ti,  Mo,  &c.,  a variety  of  relations  are 
brought  out  by  adding  or  subtracting  44. 

The  elements  C,  B,  and  Si  are  united  as  follows  : (C) 


THE  GEOMETRICAL  RATIOS. 


57 


12,  (B)  ii,  (Si)  21  = 44.  Here  he  is  misled  by  a 
faulty  determination  of  the  equivalent  of  silicon.  The 
same  difference  is  detected  in  several  other  cases.  After 
tracing  these  differences,  he  remarks  that  this  number 
44-45  plays  an  important  part  in  the  science  of  stoichio- 
metry and  the  relations  which  depend  upon  it  are  sup- 
ported, in  some  cases  at  least,  in  a remarkable  manner, 
by  analogies  of  atomic  volume.  These  analogies  are 
pointed  out  in  a series  of  tables.  The  author  concludes 
that  this  relation  extends  to  48  of  the  known  elements, 
to  all  whose  equivalents  are  well  known  except  the  group 
O,  S,  Se,  and  Te  “substances  which  stand  alone  and 
unmistakably  apart  from  the  other  elements.”  This 
same  difference  44  is  beginning  again,  in  these  later  days, 
to  attract  attention  in  considerations  of  the  atomic  weights. 
Tea  did  not  make  much  use  of  the  negative  equivalents 
given  by  him  in  his  tables,  still  they  were  criticized.  So  in 
a subsequent  paper  (40)  he  met  these  criticisms  by 
the  statement  that  these  numbers  with  the  negative  sign 
were  mere  mathematical  abstractions  and  of  course  did 
not  mean  “ less  than  nothing.”  Considered  in  connec- 
tion with  the  operations  by  which  they  were  produced, 
they  are  full  of  significance. 

45.  The  Geometrical  Ratios. — Another  paper  (45) 
was  devoted  to  what  he  called  geometrical  ratios.  He  first 
offered  as  an  explanation  of  the  arithmetical  relations,  al- 
ready discussed,  the  hypothesis  that  the  common  differ- 
ence in  a series  of  elements  might  represent  the  equivalent 
number  of  a substance,  as  yet  undetermined,  which  by 


58 


THE  PERIODIC  LAW. 


its  combination  in  varying  proportions  gave  rise  to  the 
successive  terms  of  the  series. 

He  noted  that  if  we  take  two  substances  and  examine 
the  ratio  which  subsists  between  the  numbers  repre- 
senting their  atomic  weights,  we  may  find,  in  certain 
cases,  that  it  is  identical  with  the  ratio  subsisting 
between  the  atomic  weights  of  two  other  substances  and 
so  on  through  a considerable  number  of  elements.  The 
ratio  between  the  atomic  weights,  for  instance,  of  O and 
N is  that  of  four  to  seven,  so  likewise  is  that  between 
Zr  and  K ; or  K and  Ba.  He  then  gave  a table  in 
which  the  elements  are  arranged  according  as  they  give 
this  oxygen-nitrogen  ratio  of  y,  and  a second  table  for 
the  carbon-nitrogen  or  f ratio. 

A different  mode  of  expressing  these  relations  is  gotten 
when  instead  of  adopting  the  equivalent  of  one  element 
as  oxygen  or  hydrogen  as  a permanent  unit,  we  suc- 
cessively make  those  of  the  left-hand  members  of  the 
proportion  the  units,  say  ioo,  then  of  course  all  the 
right-hand  members  will  have  the  equivalent  175,  or  for 
the  second  ratio  some  different  number  will  be  gotten. 

46.  Other  Regularities. — These  ratios  are  traced  in 
sundry  ways  for  many  elements.  The  author  did  not 
regard  them  as  having  any  very  evident  explanation. 
He  further  traced  various  obscure  relationships  in  the 
group  of  the  halogens,  thus:  1=  10  Cl  — 12  F;  Cl  = 

12  Br  — 7I  . , , . . , . . 

— etc.,  etc.  A table  is  also  given,  beginning 

with  Mg=  12,  and  using  oxj'gen  as  an  increment,  and 
the  coincidences  with  known  elements  are  noted,  and 


prout’s  hypothesis. 


59 


also  another  table  beginning  with  0 = 8 and  using  the 
same  increment.  The  author  very  aptly  added  that  it  is 
difficult  to  fix  the  exact  importance  to  be  attached  to 
the  various  numerical  regularities  hitherto  observed 
among  the  atomic  weights,  some  being  mere  casual  co- 
incidences, and  sometimes  relations  remarkably  exact 
and  symmetrical  may  exist  between  the  atomic?weights 
of  bodies  which  show  no  analogies  in  their  general 
properties. 

47.  Physical  or  Absolute  Atoms. — In  a last  paper 
(45)  the  author  makes  use  of  the  work  of  Gustav 
Tchermak,  on  the  subject  of  the  law  of  volumes  of  liquid 
chemical  compounds,  in  which  he  maintains  that  many 
of  the  substances  usually  classed  as  elements,  comport 
themselves  as  compound  bodies  and  that  it  is  possible  to 
determine  from  their  physical  properties  the  number  of 
“physical”  or  absolute  atoms  which  he  supposes  are 
contained  in  a chemical  atom  of  such  a body.  This 
theory  Tea  combines  with  some  of  the  numerical  rela- 
tions formerly  noted  by  him. 

48.  Dumas’  Extension  of  Prout’s  Hypothesis. — Dumas 
had  taken  up  and  put  new  life  into  the  hypothesis  of 
Prout  in  1840.  A little  later  he  had  adopted  with  en- 
thusiasm the  suggestion  of  Marignac  that  the  hypothesis 
be  extended  to  the  half-atom  of  hydrogen.  In  1859  he 
reiterated  his  adhesion  to  the  hypothesis  and  extended  it 
still  further  to  the  fourth  atom  of  hydrogen,  this  having 
become  necessary  because  of  more  accurate  determina- 
tions and  the  certainty  that  fractional  atomic  weights 
would  have  to  be  used  for  some  of  the  elements.  He 


6o 


THE  PERIODIC  DAW. 


found  twenty-two  atomic  weights  to  be  whole  multiples  of 
hydrogen  ; seven  atomic  weights  were  multiples  of  the 
half  atomic  weights : and  three  were  multiples  of  the 
fourth  atom. 

Further  he  found  that  analogous  bodies  have  identical 
atomic  weights  or  those  with  very  simple  relations  be- 
tween them.  And  again,  the  equivalents  of  elements  in 
the  same  family  furnish  laws  analogous  to  those  fur- 
nished by  the  numbers  representing  the  equivalents  of 
organic  radicals  belonging  to  the  same  natural  series. 

He  formulated  the  two  following  propositions. 

1.  The  natural  classification  of  non-metallic  bodies 
is  based  on  the  character  of  the  compounds  which  they 
form  with  hydrogen,  on  the  ratio  in  volumes  of  the  two 
elements  which  combine,  and  in  the  mode  of  conden- 
sation. 

2.  The  natural  classification  of  the  metals  and  in  gen- 
eral, of  the  bodies  which  do  not  unite  wTith  hydrogen, 
should  be  based  on  the  character  of  the  compounds 
which  they  form  with  chlorine,  and  so  far  as  possible  on 
the  ratio  in  volumes  of  the  two  elements  which  combine 
and  the  mode  of  condensation. 

49.  Criticisms  of  the  Work  of  Dumas. — Schneider 
(33)  regarded  the  work  of  Pettenkofer  and  Dumas  as 
important  steps  toward  the  upbuilding  of  a natural  sys- 
tem. He  criticised  the  propositions  of  Dumas  in  detail, 
differing  with  him  especially  as  to  several  elements 
having  the  same  atomic  weight.  He  pointed  out  further 
that  the  extension  of  the  hjrpothesis  of  Prout  to  the 
fourth  of  an  atom  of  hydrogen  really  deprived  it  of  all 


THE  WORK  ACCOMPLISHED.  6l 

interest  and  value.  The  extension  could  just  as  well  be 
carried  out  to  the  eighth  of  an  atom  and  so  ad  infinitum. 

Schafarik  (38)  thought  that  the  observations  of  Dumas 
upon  the  atomic  weights  opened  up  brilliant  glimpses. 
He  regarded  them  as  the  last  and  clearest  expression  of 
a movement  of  the  age.  “ If  the  simple  bodies  group 
themselves  into  series  as  do  the  organic  still  many  blanks 
remain  to  be  filled.  But  when  one  sees  what  Gerhardt’s 
series  have  accomplished  for  the  organic  chemist  he  can 
not  drive  out  similar  expectations  for  the  inorganic.  And 
when  once  the  series  of  simple  radicals  are  full,  we  will 
surely  learn  to  accomplish  with  them  what  we  can  already 
partially  do  for  the  compound  radicals — build  them  up.” 

50.  The  Work  Accomplished. — From  the  extracts 
which  have  been  given,  it  has  been  seen  that  the  decade 
from  1850  to  i860  was  one  of  great  activity  in  the  line  of 
discovering  all  sorts  of  numerical  relations  between  the 
atomic  weights,  a sort  of  blind  groping,  feeling  that 
there  was  an  underlying  law  to  be  discovered  and 
reaching  out  after  it  without  avail.  It  is  not  strange 
that  many  of  the  relations  should  have  been  very  fanci- 
ful. Nor  is  it  wonderful  that  they  failed  to  see  the  law 
at  the  bottom  of  these  regularities  or  the  explanation  of 
them.  The  natural  law  could  not  be  discovered  with 
such  incorrect  atomic  weights  as  were  at  their  service. 
Even  with  our  approximately  correct  weights  we  are 
far  from  seeing  the  explanation  of  many  of  these  same 
relations.  The  first  attempt  at  arranging  the  elements 
in  an  ascending  series  according  to  the  magnitude  of  the 
atomic  weights,  was  in  this  decade.  This  was  done  by 


62 


THE  PERIODIC  LAW. 


Gladstone,  but  failed  of  any  important  results,  because 
of  errors  in  the  atomic  weights.  The  first  diagrammatic 
representation  of  the  elements,  based  upon  the  atomic 
weights,  fell  also  in  this  period,  Mercer  having  made  the 
first  diagram.  Lastly,  the  analogy  to  the  compound 
radicals  and  homologous  series  was  first  noted  and  dis- 
cussed. Still,  one  must  confess  that  the  brilliant  prom- 
ise of  the  beginning  of  the  period  was  far  from  fulfilled, 
and  it  was  perfectly  natural  that  chemists  generally, 
should  begin  to  regard  the  whole  subject  with  indiffer- 
ence or  even  with  ridicule. 


CHAPTER  III. 

THE  IMMEDIATE  FORERUNNERS  OF  THE  PERIODIC  LAW. 

51.  The  New  Conditions. — From  i860  on,  the  way  be- 
came clearer,  and  in  the  succeeding  work  we  catch  glimp- 
ses of  the  great  natural  law  until  at  the  close  of  the  decade 
the  law  stands  fairly  stated.  At  first  little  attention  was 
paid  to  the  papers  containing  it,  or  they  were  even  laughed 
at,  for  chemists  had  become  tired  of  these  endless  symme- 
tries and  regularities  offered  without  explanation  and  with- 
out use.  We  will  see  too  that  occasionally  some  returned 
to  the  same  sort  of  speculations  which  characterized  the 
sixth  decade,  oblivious  of  the  changes  which  had  come 
over  the  field  of  work.  Two  factors  enter  largely  into 
the  improvement  in  the  character  of  the  work  of  the 
period.  Chemists  were  now  in  the  possession  of  a fairly 
accurate  set  of  atomic  weights  and  a more  extended 
knowledge  of  the  elements  and  their  compounds. 
Several  elements  were  added  to  the  list  by  means  of  the 
spectroscope  and  expectations  were  aroused  that  yet 
others  might  be  discovered. 

52.  Stas’  Opposition  to  Prout’s  Hypothesis. — The 
last  serious  conflict  over  this  hypothesis  took  place  be- 
tween Stas  and  Marignac  from  i860  to  1866.  In 
order  to  test  the  truth  of  this  hypothesis  so  earnestly  con- 
tended for  by  his  old  master  and  co-worker,  Dumas,  Stas 
undertook  a re-determination  of  many  of  the  more  im- 
portant atomic  weights  with  a degree  of  care  and  accuracy 
never  before  attained.  The  atomic  weight  of  silver  was 
made  the  central  factor  in  many  of  these  determination. 


64 


THE  PERIODIC  LAW. 


Stas  tells  us  (36)  that  when  he  undertook  his  researches  he 
had  “ an  almost  absolute  confidence  in  the  correctness  of 
Prout’s  hypothesis.”  He  had  indeed  assisted  Dumas  in 
his  memorable  revision  of  the  atomic  weight  of  carbon 
which  had  done  so  much  to  reinstate  this  theory.  As 
his  newer  researches  progressed,  doubts  gradually 
arouse  within  him.  His  results  for  silver,  chlorine, 
lead,  potassium  and  other  elements  were  clearly  not 
in  accord  with  the  hypothesis  in  its  original  form  and 
so  he  was  forced  to  declare  against  the  hypothe- 
sis. Marignac  (37)  reasoned  from  Stas’ own  results  that 
Prout’s  Hypothesis  was  substantiated  rather  than  dis- 
proved. He  made  use  of  the  two  stock  arguments  of  the 
Proutians  ; that  Stas’  numbers  were  very  close  approxi- 
mations to  whole  numbers  and  hence  could  be  considered 
as  such,  and  that  those  approximations  were  too  num- 
erous to  be  accidental.  This  fatal  error  of  rounding  off 
fractions  into  whole  numbers  was  the  very  thing  which 
mislead  Prout  at  the  beginning  and  with  him  there  was 
far  more  excuse  for  it.  Marignac  further  said  that 
should  future  determinations  of  other  elements  give  simi- 
lar approximations  he  would  feel  assured  of  the  existence 
of  some  fundamental  cause  which  brought  about  the 
multiple  relation  of  the  atomic  weights  and  subordinate 
causes  which  modified  it.  He  thought  that  Prout’s  Law 
deserved  to  rank  with  that  of  Gay  Lussac  or  of  Mariotte. 

In  another  place  (61)  Marignac  speaks  of  Prout’s 
Law  as  one  of  those  not  absolute  but  only  approximate 
laws,  like  many  other  Natural  Laws,  and  says  in  regard 
to  the  assumption  of  a primal  matter,  or  protyle,  that  its 


OTHER  NUMERICAL  RELATIONS.  65 

atomic  weight  could  be  taken  as  small  as  might  be  nec- 
essary. 

It  could  well  be  classed  then  with  what  Pettenkofer 
calls  “the  attractive  and  misleading  simple  laws. of 
Nature.’’  The  “rounding-off’’  passion  was  called  by 
Berzelius  most  aptly  ‘ ‘ Multiplen-Fieber.  ’ ’ 

53.  Other  Numerical  Relations. — The  craze  for  search- 
ing out  such  regularities  as  has  been  recorded  in  the 
previous  chapter  seems  to  have  largely  subsided.  Most 
of  the  work  from  now  on  shows  a marked  difference  in 
aim  and  method.  There  is  mainly  a striving  after 
classification,  not  disjointed  triads,  nor  unconnected 
families,  but  a continuous  series  of  some  sort.  Besides 
most  of  the  work  now  before  us  is  tinged  more  or  less 
with  the  idea  of  periodicity.  Still  there  are  a few  of  the 
old  style  of  numerical  relations  to  be  mentioned.  They 
can  best  be  considered  together. 

In  1864  a short  article  appeared  in  the  London  Chemi- 
cal News  (48)  headed  “ Numerical  Relations  of 
Equivalent  Numbers’’  and  signed  “ Studiosus.”  In 
this  it  was  noted  that  the  atomic  weights  of  the  elemen- 
tary bodies,  with  few  exceptions,  were  either  exactly  or 
very  nearly  multiples  of  eight.  This  can  be  compared 
with  the  work  of  Dumas  and  Pettenkofer  of  which  Stud- 
iosus seems  ignorant. 

Newlands  opposed  this  generalization.  The  matter 
was  further  discussed  by  Noble  (51)  who  disapproved 
of  using  the  term  “law”,  as  Studiosus  had  done,  for 
such  relations.  Some  of  these  he  said,  were  interesting, 
others  were  rubbish.  Other  brief  notes  on  the  subiect 


66 


THE  PERIODIC  LAW. 


appeared  from  “Inquirer”  and  from  “Studiosus”,  and 
there  the  matter  rested.  The  fact  that  many  writing 
upon  these  subjects  concealed  their  identity  under 
fictitious  names  would  indicate  that  confidence  had  been 
lost  in  them  and  that  they  were  looked  upon  with  dis- 
favor. 

54.  Parallelism  Revived. — Several  years  later  (1869) 
an  anonymous  paper  appeared  (68)  in  the  American  Sup- 
plement to  the  London  Chemical  News.  This  paper  con- 
sidered the  parallelism  of  the  elements  in  a different  way 
from  the  Double  Parallelism  of  Dumas  and  in  a broader 
sense,  though  the  ideas  do  not  greatly  differ.  The  diagram 
given  is  similar  in  some  respects  to  some  of  the  diagram- 
matic representations  of  the  Periodic  Law  which  appeared 
a number  of  years  afterwards,  though  it  is  evident  that 
this  unknown  author  had  no  idea  of  the  law  in  making 
his  diagram.  The  prominent  idea  with  him  was  the  par- 
allelism, or  pairing  of  the  elements. 

A central  vertical  line  represented  the  increase  in 
atomic  weights  and  the  different  elements  were  placed 
along  it  at  heights  corresponding  to  their  atomic  weights 
and  at  such  distances  as  to  throw  those  of  the  same  series 
in  columns  together. 

“The  atomic  weights  seem  to  arrange  themselves  on 
the  diagonal,  in  parallel  shelving  lines ; also  there  is  a 
correspondence  between  the  series  of  artiads  andperissads 
which  have  the  highest  atomic  weights,  that  is  to  say,  Na, 
K,  Rb,  Cs,  and  T1  on  the  one  hand  and  Mg,  Ca,  Sr,  Ba, 
and  Pb  on  the  other,  inasmuch  as  they  form  strong 
bases  and  peroxides  but  no  suboxides  or  acids.” 


THE  PAIRING  OF  THE  ELEMENTS.  67 

And  so  this  parallelism  was  traced  for  the  two  series 
having  the  next  highest  atomic  weights  &c.  Also 
special  resemblances  were  pointed  out  between  the  ele- 
ments occupying  corresponding  places  in  the  series  as 
C and  F,  S and  P,  Ca  and  K,  & c. 

The  author  then  observed  that  the  regularity  to  be  de- 
tected is  certainly  a very  rude  one  but  “considering  that 
every  different  combination  of  molecular  elasticities  (as 
shown  by  spectral  lines)  must  give  a new  set  of  proper- 
ties and  considering  that  only  about  sixty  elementary 
substances  out  of  the  myriads  which  might  exist  are 
known  to  us,  we  ought  to  expect  no  more  accurate 
classification  of  them  than  could  be  made  of  the  animal 
kingdom,  if  only  sixty  animals  were  known.’’ 

55.  The  Pairing  of  the  Elements. — A short  time 
before  the  appearance  of  the  article  just  discussed, 
another  (69)  was  published  in  the  same  journal,  also 
anonymous,  and  dealing  with  a sort  of  parallelism. 

Here,  too,  a table  was  given,  in  which  the  elements  were 
arranged  in  two  columns  according  to  their  even  or  odd 
valencies,  and  at  the  same  time  observing  the  order  of 
their  atomic  weights.  It  was  claimed  that  an  inspec- 
tion of  the  table  showed  that  the  elements  were  brought 
into  “ something  like  a natural  relation  with  one 
another.”  “Where  the  atomic  weights  agree  in  the 
two  columns  there  is  a still  further  agreement  between 
the  corresponding  elements ; the  element  of  even  val- 
ence is  paired  or  mated  with  an  element  of  odd  valence. 
Probably  for  each  column  there  is  a progression  of  prop- 
erties from  the  top  to  the  bottom,  in  the  order  and  in  the 


68 


THE  PERIODIC  LAW. 


proportion  of  the  numbers,  and  the  discovery  of  such 
properties  is  a fair  and  open  problem.” 

‘‘Also,  the  column  readily  breaks  up  into  smaller  col- 
umns, or  groups.  The  peculiar  relation  of  the  artiads 
and  perissads  in  Group  I is  very  striking.  On  one  side 
are  all  the  metals  of  the  known  alkalies  and  each  is 
paired  with  a well-known  alkaline  earth.” 

‘‘The  standing  out  unpaired  of  H,  N,  P,  As,  Sb,  and 
Bi,  is  very  noticeable,  for  these  are  the  only  unmated 
perissads.  There  are  many  unmated  artiads,  and  it  is 
noticeable  that  many  of  them  occur  together.  It  is  pos- 
sible that  they  may  be  filled  by  the  discovery  of  new 
elements.” 

The  author  thought  that  more  alkalies  might  be 
looked  for. 


Artiads. 

Perissads. 

Artiads. 

Perissads. 

G1 

9 

H 

1 

Co 

58-8 

C 

12 

Li 

7 

Yt 

61.7 

B 

11 

Cu 

634 

N 

14 

Zn 

65.2 

O 

16 

F 

19 

In 

72 

Mg 

24 

Na 

23 

As 

75 

A1 

27.4 

Se 

794 

Br 

80 

Si 

28 

Sr 

87.6 

Rb 

85.4 

P 

3i 

Zr 

89.6 

S 

32 

Cl 

35-5 

Da 

93-6 

Cs 

94 

Ca 

40 

K 

39-r 

Mo 

96 

Ti 

50 

Ru 

104.4 

Or 

52.2 

V 

51-4 

Rh 

1044 

Mn 

55 

Pd 

106.6 

Ag 

108 

Fe 

56 

Cd 

112 

Ni 

00 

06 

LO 

Eb 

112.6 

&c., 

&c., 

&c., 

&c. 

atomic  weights  and  densities. 


69 


hi 

THE  SMALT  GROUPS. 

I. 

G1 

Na 

Mg 

K 

Ca 

&c. 

&c. 

F 

II. 

O 

Cl 

S 

Br 

Se 

I 

Te 

Ag 

III. 

Pd 

Au 

Pt 

Pb 

T1 

&c. 

56.  Classification  by  the  Atomicities. — It  should  be 
mentioned  in  this  connection  that  in  1864  Williamson 
(50)  had  presented  before  the  Royal  Institution  a 
“ Classification  of  the  Elements  in  Relation  to  their 
Atomicities.”  Much  credit  is  due  Williamson  for  assist- 
ing in  the  introduction  of  Cannizzaro’s  views  concerning 
the  atomic  weights  among  English  chemists  and  in  sug- 
gesting the  same  changes  in  Gerhardt’s  system,  which 
had  been  chiefly  used  up  to  that  time.  This  put  a new 
and  fairly  correct  table  in  the  hands  of  chemists. 

57.  Relation  between  the  Atomic  Weights  and  Den= 
sities. — A new  line  of  research  was  struck  out  by  Fleck 
(58)  in  1864  by  his  work  upon  the  ” Relations 
Between  the  Chemical  Equivalents  and  the  Densities  of 
Bodies.”  Intimations  of  some  sort  of  connection 
between  the  atomic  weights  and  the  properties  lie,  of 


7° 


THE  PERIODIC  LAW. 


course,  in  the  idea  of  the  triads  and  in  much  of  the  pre- 
ceding work,  but  they  were  not  clear.  Here  we  have  a 
distinct  search  for  such  relations,  though  not  a very  suc- 
cessful one.  The  day  was  still  some  distance  off  when 
the  dependence  of  the  properties  upon  the  atomic  weights 
would  come  to  be  recognized. 

Fleck  found  that  the  simple  bodies,  or  elements,  form 
several  groups  in  which  the  relation  of  the  equivalents  to 
the  square  of  the  density  is  invariable,  and  these  con- 
stant volumes  are  generally  entire  multiples  of  the  value 
borne  to  potassium. 

58.  Brodie’s  Ideal  Chemistry. — This  is  perhaps  the 
best  place  to  mention  the  efforts  of  Brodie  (66)  to  sub- 
stitute a new  chemical  theory  and  system  in  opposition 
to  the  atomic  theory.  It  appeared  as  a long  article  of  one 
hundred  pages  in  the  Journal  of  the  London  Chemical 
Society,  and  was  discussed  and  antagonized  by  many 
authors,  as  Jevons,  Williamson,  Odling,  Kekule,  Ward, 
Crum- Brown,  and  others. 

The  paper  is  a speculative  one  and  is  referred  to  here 
because  of  the  attention  aroused  by  it,  because  it  is 
quoted  by  later  authors,  and  because  of  its  bearing  upon 
that  side  of  the  subject  of  this  treatise,  which  was  often 
adverted  to  in  the  earlier  speculations  and  which  under- 
lies much  of  the  thought  and  work  upon  the  Periodic 
Law,  namely,  the  composite  nature  of  the  elements. 

Brodie  discussed  first  the  inadequacy  of  the  chemical 
symbols.  He  suggested  as  a foundation  for  a new  and 
more  correct  principle  the  unit  of  each  body  in  a gaseous 
condition,  viz.,  that  unit  of  gaseous  weighable  matter 


brodie’s  ideal  chemistry. 


7r 


which  fills  a space  of  1000  cc.  at  o°  and  760  mm.  pres- 
sure. 

This  unit  of  mass,  empty,  may  be  designated  I.  Now 
let  S designate  the  operation  by  which  the  unit  of  mass 
is  filled  with  the  unit  of  weight,  then  S;,I  would  mean 
this  unit  of  mass  filled  with  a stuff  of  three  times  the 
condensation,  etc.  Such  a system  of  symbols  would 
give  at  the  same  time  the  operation  and  its  result.  The 
symbol  of  the  compound  is  at  the  same  time  the  symbol 
according  to  which  the  combination  took  place.  The 
following  may  be  taken  as  examples  : 

Unit  of  mass  = I S = t2 

H = a H2S  = at 

0=  x2 

H20  = ax  SO;i  = tx3 

H202  = ax2  H2S04  = atx4 

Thus  the  hypothesis  is  made  that  the  symbol  of  hydro- 
gen be  a,  and  hydrogen  is  formed  by  one  of  the  above- 
mentioned  operations.  Then  oxygen  (x)  represents  two 
operations  ; the  same  also  of  wTater. 

This  use  of  symbols,  according  to  Brodie,  should  give 
us  an  insight  into  the  nature  of  matter.  There  are,  he 
thinks,  different  classes  of  elements. 

1.  Those  which  were  formed  by  one  operation  (as  H 
and  Hg.) 

2.  Those  in  whose  formation  two  similar  operations 
were  carried  out. 

3.  Those  which  must  be  designated  compound  (as  Cl 
out  of  a,  and  an  unknown  element  c.)  In  these  com- 
pound elements  we  come  across  units  of  unknown  ele- 


72 


THE  PERIODIC  DAW. 


ments,  as  c,  i,  n.  Whether  these  exist  or  not,  Brodie 
does  not  profess  to  know.  Their  unit  symbols  answer 
every  condition  of  real  existence.  Perhaps  they  were 
once  free  upon  the  earth,  but  have  become  indissolubly 
combined  upon  its  coolings.  Brodie  says  he  does  not 
aim  at  proving  the  existence  of  a primal  matter,  but 
only  to  make  the  existence  of  these  compound  elements 
probable. 

It  is  scarcely  necessary  to  subject  such  speculations  to 
criticism. 

59.  Brodie’s  Conception  of  the  Genesis  of  the 
Elements. — With  regard  to  the  existence  of  these 
elements,  out  of  which  our  present  elements  are  made 
up,  he  says  : 

“We  may  conceive  that  in  remote  time  or  in  remote 
space,  there  did  exist  formerly,  or  possibly  do  now  exist, 
certain  simpler  forms  of  matter  than  we  find  on  the  sur- 
face of  our  globe,  a,  x,  e»  y,  and  so  on.  We  may  con- 
sider that  in  remote  ages  the  temperature  of  matter  was 
much  higher  than  it  is  now,  and  that  these  other  things 
existed  then  in  the  state  of  perfect  gases,  separate  ex- 
istences, uncombined. 

“We  may  then  conceive  that  the  temperature  began 
to  fall,  and  these  things  to  combine  with  one  another 
and  to  enter  into  new  forms  of  existence,  appropriate  to 
the  circumstances  in  which  the)'  were  placed.  * * * 

We  may  further  consider  that  as  the  temperature  went 
on  falling,  certain  forms  of  matter  became  more  perma- 
nent and  more  stable,  to  the  exclusion  of  other  forms. 


TELLURIC  SCREW  OF  DE  CHANCOURTOIS.  73 

We  may  conceive  this  process  of  the  lowering  of  the  tem- 
perature going  on,  so  that  these  substances,  when  once 
formed,  could  never  be  decomposed,  in  fact,  that  the 
resolution  of  these  bodies  into  their  component  elements 
could  never  occur  again.  You  would  then  have  some- 
thing of  our  present  system  of  things. 

“Now,  this  is  not  purely  an  imagination,  for  when  we 
look  upon  the  surface  of  our  globe,  we  have  actual  evi- 
dence of  similar  changes  in  Nature.  When  we  look  at 
some  of  the  facts  which  have  been  revealed  to  us  by  the 
extraordinary  analyses  which  have  been  made  of  the 
matter  of  distant  worlds  and  nebulae,  by  means  of  the 
spectroscope,  it  does  not  seem  incredible  to  me  that 
there  may  even  be  evidence,  some  day,  of  the  indepen- 
dent existence  of  such  things  as  x and_y.” 

It  is  perhaps  not  so  very  surprising  that  such  baseless 
speculations  as  these  should  have  received  more  atten- 
tion and  more  approval  than  the  Law  of  Octaves  of 
Newlands.  Where  boundless  space  and  limitless  possi- 
bilities are  taken  into  consideration,  no  proof  is  possible 
and  none  can  be  required,  and  such  free  flights  of  the 
imagination  are  always  attractive  to  certain  minds. 

60.  The  Telluric  Screw  of  De  Chancourtois. — It  is  to 

De  Chancourtois,  an  engineer  and  geologist,  that  the 
credit  of  being  the  first  to  devise  a symmetrical  arrange- 
ment of  the  elements  is  generally  given.  He  may  in 
some  measure  be  regarded  as  the  originator  of  the 
periodic  law,  though  his  work  lay  unnoticed  for  thirty 
years  and  the  periodic  law  was  developed  independently 


74 


THE  PERIODIC  LAW. 


of  it.  In  1862  (46)  he  presented  to  the  French  Acad- 
emy of  Science  a paper  on  a “ Natural  Classification  of 
the  Simple  or  Radical  Bodies  entitled  the  Telluric 
Screw  (Vis  Tellurique).”  Several  communications  fol- 
lowed and  it  was  all  finally  put  in  the  form  of  a 
lithographic  table  which  summed  up  all  his  ideas 
and  was  accompanied  by  certain  general  considerations 
on  the  numerical  character  of  the  simple  bodies,  as  well 
as  on  the  verifications  -which  spectral  anatysis  might 
furnish.  In  this  paper  is  found  the  very  explicit  asser- 
tion as  ‘ ‘ the  first  general  conclusion  from  his  work.  ’ ’ 
‘ ‘ Les  proprietes  des  corps  sont  les  proprietes  des  nom- 
bres.”  The  most  important  part  of  the  Periodic  Law  is 
that  the  properties  of  the  elements  are  determined  by  and 
are  dependent  upon  the  atomic  weights.  De  Chancour- 
tois’  statement  is  obscure  but  may  be  looked  upon  as 
conveying  in  part  the  same  idea. 

The  fundamental  idea  of  the  Telluric  Screw  consisted 
in  writing  the  values  of  the  atomic  weights  along  the 
generatrix  of  a vertical  cylinder,  the  circular  base  of 
which  was  divided  into  sixteen  equal  parts,  sixteen  be- 
ing the  atomic  weight  of  oxygen.  If  we  then  trace  upon 
the  cylinder  a helix  with  an  angle  of  forty-five  degrees 
to  its  axis,  each  point  of  the  helix  may  be  considered  as 
the  characteristic  point  of  a simple  body,  the  atomic 
weight  of  which,  proportional  to  the  corresponding 
length  of  the  spiral,  will  be  road  upon  the  generatrix 
which  passes  by  this  point.  At  each  turn,  the  helix  re- 
turns on  one  and  the  same  perpendicular  at  distances 
from  the  summit  of  the  cylinder  which  are  multiples  of 


TELLURIC  SCREW  OF  DE  CHANCOURTOIS.  75 

sixteen,  and  mark  the  bodies  whose  atomic  weights  con- 
form to  this  condition. 

“In  the  same  manner  the  various  points  of  intersection 
of  the  helix  with  any  of  the  sixteen  principle  genera- 
trices, traced  from  the  divisions  of  the  circular  base, 
correspond  to  elements  whose  atomic  weights  differ 
among  themselves  by  sixteen,  or  by  a multiple  of  sixteen. 
Lastly  , if  after  having  developed  the  cylinder  upon  a plane 
which  transforms  the  helix  into  a series  of  straight 
parallel  segments,  we  join  by  a straight  line  any  two 
points  taken  upon  two  segments,  after  coiling  up,  this 
right  line  will  produce  a secondary  helix,  and  the  inter- 
sections of  this  latter  with  the  various  turns  of  the  prin- 
cipal helix  will  mark  bodies  for  which  the  differences  of 
the  atomic  weights  will  be  multiples  of  a constant  quan- 
tity. In  this  manner  the  Telluric  Screw,  by  simply 
drawing  right  lines,  enables  us  to  show  numerical  rela- 
tions which  it  would  have  been  less  easy  to  detect  by  a 
mere  inspection  of  the  numbers.’’ 

“The  relation  of  the  properties  of  the  bodies  are  mani- 
fested by  simple  relations  of  position  of  their  character- 
istic points  : and  then,  each  of  the  helices  carried  through 
two  characteristic  points  and  passing  by  several  other 
points,  or  merely  in  their  proximity,  shows  relations  of 
properties  of  a certain  kind,  the  analogies  or  the  con- 
trasts being  manifested  by  certain  numerical  orders  of 
succession  like  the  immediate  sequence  or  the  alterna- 
tions at  diverse  periods.” 

De  Chancourtois  thus  gives  a classification  of  the  ele- 
ments according  to  their  atomic  weights  and  indicates 


76 


THE  PERIODIC  LAW. 


the  idea  of  periodicity.  He  says,  “ We  cannot  refrain 
from  remarking  the  predominance  of  the  number  7 in 
the  types  of  the  groups  occupying  the  spiral  which  are 
best  filled  out.” 

In  his  pamphlet,  published  in  1863,  he  speaks  of 
‘ ' direct  developments  of  the  system  which  enable  us  to 
perceive  at  the  same  time  approximations  of  the  series 
of  numerical  characteristics  to  the  series  of  musical 
sounds,  and  to  that  of  the  bands  and  rays  of  the  spec- 
trum.” 

For  this  resume  of  the  work  of  de  Chancourtois  I am 
indebted  to  Lecoq  de  Boisbaudran  and  A.  de  Lap- 
perent  (198),  and  Crookes  (199).  It  has  been  compared 
with  the  original.  In  their  critique  of  the  work  they  say 
that  they  are  far  from  pretending  that  the  theory  of  the 
screw  is  free  from  faults,  and  that  the  author  had  not 
grafted  upon  his  work  many  considerations  which  it 
would  have  been  better  to  leave  out.  Several  approxi- 
mations were  inaccurate  or  were  strained,  and  some  of 
them  evince  too  free  a use  of  the  imagination.  De  Chau- 
courtois  started  outwith  the  idea  that  in  the  natural  series 
the  differences  between  the  atomic  weights  ought  to  be 
constant.  Gaps  were  filled  up  by  imagining  new  varieties 
of  known  simple  bodies  which  he  called  Secondary 
Characters,  and  this  often  led  him  to  mistaken  ana- 
logies. 

61.  The  Work  of  Newlands. — A second  worker,  to 
whom  credit  is  due  as  to  one  who  grasped  some  of 
the  truths  of  the  Periodic  Arrangement,  was  John  A.  R. 


THE  WORK  OF  NEWUNDS. 


77 


Newlands.  His  work  followed  immediately  upon  that 
of  de  Chancourtois,  but  was  quite  independent  of  it. 
His  first  paper  (47)  was  devoted  to  the  consideration  of 
some  numerical  relations  between  the  atomic  weights. 
These  relations  were  in  part  along  the  line  of  the  old 
triads,  thus  zinc  was  pointed  out  as  the  mean  between 
magnesium  and  cadmium,  copper  between  cobalt  and 
zinc.  In  the  group  of  the  alkalies,  one  of  lithium  and 
one  of  potassium  made  two  of  sodium  ; one  of  lithium 
and  two  of  potassium  made  one  of  rubidium,  etc.  Sim- 
ilar relations  were  observed  for  other  groups.  He  also 
endeavored  to  show  a certain  kind  of  symmetry  when 
the  lowest  member  of  a group  was  subtracted  from  the 
next  higher  member  and  when  the  lowest  member  of  a 
triad  was  deducted  from  the  highest.  These  were  not 
very  obvious.  In  his  first  work  he  used  the  old  atomic 
weights  but  speedily  abandoned  them  for  those  of  Cann- 
izzaro. 

In  a second  paper  (53)  he  gave  a table  containing  the 
elements  arranged  in  the  order  of  their  atomic  weights. 
In  a side  column  the  differences  between  these  weights 
were  given,  each  being  deducted  from  the  one  next  higher 
in  the  scale.  He  failed  to  find  any  regularity  in  these 
differences,  in  fact  the  table  was  made  to  disprove  the 
supposed  law  of  one  “ Studiosus,”  who  had  maintained 
that  the  atomic  weights  of  the  elementary  bodies  were, 
with  few  exceptions,  either  exactly  or  very  nearly  multiples 
of  eight,  and  whose  work  has  been  already  mentioned. 
This  has  been  claimed  as  the  first  arrangement  of  the 
elements  in  the  order  of  their  atomic  weights,  but 


78 


THE  PERIODIC  LAW. 


was  preceded  by  nearly  ten  years  by  the  arrangement 
of  Gladstone,  in  which,  however,  the  atomic  weights 
were  so  faulty  that  no  regularities  were  discovered, 
and  it  is  also  antedated  by  the  arrangement  of  de  Chan- 
courtois.  The  remainder  of  his  paper  was  devoted  to  a 
discussion  of  some  triads  and  he  noted  the  recurrence  of 
the  number  sixteen  as  the  difference  number  between  the 
first  and  second  numbers  of  some  of  the  best  known  triads. 

62.  The  Law  of  Octaves. — It  was  in  a third  paper 
(54),  published  a month  later,  that  he  began  to  pay 
attention  to  the  possibilities  of  his  new  arrangement  of 
the  elements  in  the  order  of  their  atomic  weights.  In 
that  paper  he  stated  that  if  these  elements  are  numbered 
1,  2,  3,  &c.,  “it  will  be  observed  that  elements  having 
consecutive  numbers  frequently  either  belong  to  the  same 
group  or  occupy  similar  positions  in  different  groups.” 
“The  difference  between  the  number  of  the  lowest  member 
of  a group  and  that  immediately  above  it  is  7 ; in  other 
words,  the  eighth  element  starting  from  a given  one  is  a 
kind  of  repetition  of  the  first,  like  the  eighth  note  of  an 
octave  in  music.  The  differences  between  the  numbers 
of  the  other  members  of  a group  are  frequently  twice  as 
great;  thus  in  the  nitrogen  group,  between  N and  P 
there  are  seven  elements  ; between  P and  As  13  ; between 
As  and  Sb,  14  and  between  Sb  and  Bi , 14.” 

At  the  close  of  the  paper,  he  referred  again  to  his  triads, 
and  spoke  of  the  apparent  existence  of  triads  where  the 
middle  members  were  unknown  and  also  the  possibility  of 
Mn,  Fe,  Co,  Ni,  and  Cu,  being  the  centres  of  triads 
whose  extremes  were  unknown  or  unrecognized.  On 


EXISTENCE  OF  TRIADS. 


79 


the  discovery  of  indium,  he  hastened  to  suggest  a place 
for  it  among  the  triads  and  also  in  his  new  system  (55). 

One  year  after  his  first  announcement  of  the  new 
system  of  the  atomic  weights  in  numerical  order,  New- 
lands  published  a paper  (56),  giving  his  discovery  a 
name  and  proclaiming  it  to  be  a “law.”  The  paper  was 
entitled  “ On  the  Taw  of  Octaves.”  In  the  table  which 
he  gave,  he  transposed  some  of  the  elements  so  as  to 
bring  them  into  their  proper  groups.  He  observed  that 
elements  belonging  to  the  same  group  “ usually”  appear 
on  the  same  horizontal  line.  He  next  declared 
that  “all  the  numerical  relations  among  the  equivalents 
pointed  out  by  M.  Dumas  and  others,  including  the  well- 
known  triads,  are  merely  arithmetical  results  flowing 
from  the  existence  of  the  Daw  of  Octaves.”  Pursued 
by  what  might  well  be  called,  in  his  case  and  in  many 
others,  a mania  for  hunting  out  arithmetical  relations, 
he  tried  to  discover  some  sort  of  relationship  between 
the  numbers  given  the  elements  as  they  fall  in  their 
places  in  the  system  and  their  atomic  weights. 

63.  Explanation  of  the  Existence  of  Triads.  — He 
offered  (57)  as  an  explanation  of  the  existence  of  triads  the 
fact  that,  “in  conformity  with  the  Daw  of  Octaves,  elements 
belonging  to  the  same  group  generally'  have  numbers 
differing  by  seven  or  by  some  multiple  of  seven.  That  is 
to  say,  if  we  begin  with  the  lowest  member  of  a group,  call- 
ing it  1 , the  succeeding  members  will  have  the  numbers  8, 
15,  22,  29,  &c  respectively.  But  8 is  the  mean  between 
1 and  15  ; 15  is  the  mean  between  8 and  22  &e.  and 
therefore  as  an  arithmetical  result  of  the  Daw  of  Octaves 


8o 


THE  PERIODIC  LAW. 


tlie  number  of  an  element  is  often  the  exact  mean  of 
those  of  two  others  belonging  to  the  same  group  and 
consequently  its  equivalent  also  approximates  to  the 
mean  of  their  equivalents.” 

Newlands’  Table  of  the  elements,  as  given  in  1866,  is 
reproduced  here. 


Elements  Arranged  in  Octaves. 

No. 

No. 

No. 

No. 

H 

F 

8 

Cl 

■•15 

Co  and  Ni 

22 

Li 

Na.... 

9 

K 

Cu 

•23 

G 

• 3 

Mg  ... 

Ca 

••17 

Zn 

•24 

Bo  

• 4 

A1  ... 

Cr 

. .18 

Y 

•25 

c 

• 5 

Si 

Ti  

..19 

In 

N 

. 6 

P 

13 

Mn 

• 20 

As 

• 27 

O 

• 7 

s 

..  ..14 

Fe 

Se 

. 28 

Br 

.29 

Pd 

....  36 

Te 

••43 

Pt  and  Ir  . 

,.5o 

Rb 

•30 

Ag  ••••■ 

••••37 

Cs 

..44 

Os 

•51 

$r 

Cd 

18 

Ba  and  V • ■ 

Ho- 

Ce  and  La- 

32 

u 

...  39 

Ta 

•46 

T1 

•53 

Zr 

•33 

Sn 

• • -4° 

w 

•47 

Pb 

•54 

Di  and  Mo  34 

Sb 

41 

Nb 

.48 

Bi 

• 55 

Ro  and  Ru 

•35 

I 

...42 

Au  

.49 

Th 

• 56 

In  order  to  allow  for  certain  elements  -which  have  their 
atomic  weights  very  close  together,  as  cobalt  and  nickel, 
Newlands  modified  his  law  thus;  ‘‘The  numbers  of 
analogous  elements,  when  not  co?isecutive,  differ  by 
seven,  or  by  some  multiple  of  seven.” 


82 


THE  PERIODIC  LAW. 


64.  Criticisms  of  Newlands’  Law. — Dr.  Gladstone 
objected  to  the  arrangement  on  the  score  of  no  room 
being  left  for  elements  which  might  still  be  discovered. 
Further  there  seemed  to  be  about  as  close  an  analogy 
between  the  elements  in  the  last  vertical  column  as  be- 
tween those  in  any  horizontal  line.  Professor  G.  F. 
Foster  condemned  the  arrangement  because  of  the 
distance  placed  between  manganese  and  chromium  or 
iron  and  cobalt  and  nickel. 

In  reply  to  the  criticism  of  Gladstone,  Newlands 
said  that  the  fact  that  such  a simple  relation  existed 
now  was  presumptive  proof  that  it  would  continue  to 
exist  no  matter  how  many  elements  should  be  discovered. 
The  difference  in  the  numbers  of  the  analogous  elements 
might  be  altered  to  eight  or  any  conceivable  number 
without  destroying  the  simple  relation  between  the  num- 
bers of  analogous  elements. 

Very  little  attention  was  paid  to  this  work  of  Newlands. 
In  fact  it  was  allowed  to  drop  complete^  out  of  sight  as 
was  the  somewhat  similar  work  of  De  Chancourtois.  It 
was  not  brought  to  light  again  until  after  the  system 
of  Mendeleeff  had  become  famous. 

65.  Character  of  the  work  of  De  Chancourtois  and 
Newlands. — With  regard  to  the  work  of  these  two,  De 
Chancourtois  and  Newlands,  it  is  certain  the}1-  recognized 
the  fact  that  periods  of  seven  existed.  They  failed  to  extend 
the  idea  fully  to  properties  other  than  the  atomic  weights. 
The  arrangement  of  the  elements  in  the  order  of  their 
atomic  weights  had  been  tried  a number  of  years  before 


DE  CHANCOURTOIS’  AND  NEWUNDS’  WORK.  83 

the  papers  of  these  two  workers  appeared.  De  Chan- 
courtois  seems  to  have  had  some  glimpse  of  the  de- 
pendence of  the  properties  upon  the  atomic  weights. 
These  two  investigators  then  really  cover  many  of  the  im- 
portant points  of  the  PeriodicLaw.  Their  failure  to  impress 
their  views  upon  their  contemporaries  came  from  a lack 
of  clearness  of  statement,  from  faulty  atomic  weights 
and  arrangement,  and  from  their  complicating  matters 
and  obscuring  the  truth  by  useless  and  false  speculations. 

Mendeleeff  (181)  has  criticised  their  work  as  fol- 
lows: “In  such  attempts  at  arrangement  and  in 

such  views  are  to  be  recognized  the  real  forerunners  of 
the  Periodic  Law;  the  ground  was  prepared  for  it  between 
i860  and  1876,  and  that  it  was  not  expressed  in  a deter- 
minate form  before  the  end  of  the  decade,  may  I suppose, 
be  ascribed  to  the  fact  that  only  analogous  elements  had 
been  compared  (vid.  M.  Carey  Lea) . The  idea  of  seeking 
for  a relation  between  the  atomic  weight  of  all  the  elements 
was  foreign  to  the  ideas  then  current,  so  that  neither  the  Vis 
Tellurique  of  De  Chancourtois,  nor  the  Law  of  Octaves  of 
Newlands,  could  secure  anybody’s  attention.  And  yet 
both  De  Chancourtois  and  Newlands,  like  Dumas  and 
Strecker,  more  than  Lennsen  and  Pettenkofer,  had  made 
an  approach  to  the  Periodic  Law  and  had  discovered  its 
germs. 

“The  solution  of  the  problem  advanced  but  slowly,  be- 
cause the  facts,  and  not  the  law,  stood  foremost  in  all 
attempts ; and  the  law  could  not  awaken  a general  in- 
terest so  long  as  elements,  having  no  apparent  connection 
with  each  other,  w7ere  included  in  the  same  octave.’’ 


84 


THE  PERIODIC  LAW. 


66.  Remarks  of  Crookes  upon  the  Priority  Claims. — 

With  regard  to  the  claim  of  priority  advanced  for  De 
Chancourtois  and  Newlands  Crookes  says  (199)  “The 
Periodic  Law,  it  must  be  remembered,  when  first 
announced  was  not  immediately  accepted.  When  Mr. 
Newlands  read  his  memoir  before  the  Chemical  Society 
it  by  no  means  met  with  a very  enthusiastic  reception. 
One  gentleman  present  even  inquired,  sarcastically, 
whether  the  author  had  ever  arranged  the  elements 
according  to  the  order  of  their  initial  letters. 

“Then  came  the  announcements  by  Professors  Mende- 
leeff  and  L.  Meyer  of  their  independent  and  simultaneous 
discover  of  the  same  truth.  The  details  were  quickty 
circulated  and  discussed  in  the  scientific  press,  and  the 
respective  merits  of  the  two  savants  was  for  a time  a bone 
of  contention.  Professor  Mendeleeff  said  : It  is  possible 
that  Newlands  has  prior  to  me,  enunciated  something 
similar  to  the  Periodic  Law,  but  even  this  cannot  be 
said  of  L.  Meyer. 

When  the  successful  attempt  was  made  to  vindicate 
the  claims  of  Newlands  as  the  first  discoverer,  the  ques- 
tion was  thoroughly  rediscussed.  But  none  of  the 
savants  who  entered  into  the  question  ever  breathed  the 
name  of  De  Chancourtois.  His  memoirs  were  at  all  times 
accessible  in  the  Comptes  Rendus.  But  no  one  found 
in  them  that  meaning  which  M.  de  Boisbaudran  and  de 
Lapperent  now  assert.  They  certainty  contain  a pro- 
posal to  classify  the  elements  with  reference  to  their 
atomic  weights.  But  we  may  be  permitted  to  doubt 


FIRST  TABLE  OF  LOTHAR  MFYER.  85 

whether  they  can  be  fairly  considered  as  the  germ  of  the 
Periodic  Law. 

“ In  going  over  old  researches  we  often  find  in  them 
matter  which  we  may  now  regard  as  a forecast  of  subse- 
quent discoveries  ; but  there  is  no  sufficient  evidence 
that  the  author  disentangled  such  matter  from  accom- 
panying speculations.  In  the  memoir  (of  de  Boisbaudran 
and  de  Lapperent)  we  find  an  admission  that  such  has 
been  the  case  with  the  writings  of  M.  De  Chancourtois.” 

67.  The  First  Table  of  Lothar  Meyer. — In  the  year 
1864,  that  is,  two  years  before  the  presentation  of  New- 
lands’paper  before  the  Chemical  Society  of  London,  con- 
taining his  Law  of  Octaves,  but  about  the  time  of  his 
first  publication,  Lothar  Meyer  published  the  first  edition 
of  his  “ Modern  Theories  of  Chemistry ” (59)  and  in  it  gave 
a table  of  the  elements  arranged  horizontally  according 
to  their  atomic  weights,  so  that  analogous  elements  stood 
under  one  another  and  the  change  of  valence,  along  with 
that  of  atomic  weight,  could  be  easily  observed.  Besides, 
the  difference  numbers  between  these  weights,  taken 
horizontally,  were  also  given.  Some  elements  were  not 
included  in  the  list  and  others  were  given  inaccurately, 
thus  impairing  the  value  of  the  table.  The  second, 
third  and  fourth  series  are  given  here  as  illustrations. 


IV. 

in. 

II. 

I. 

1. 

11. 

2.  Ser. 

C 12.0 

N 14.04 

O 16.0  F 19.0 

Na  23.05 

Mg  24.0 

Diff. 

16.5 

16.96 

16.07 

16.46 

16.08 

16.0 

3.  Ser. 

Si  28.5 

P 31.0 

S 32.07  CI35.46 

K 39-13 

Ca  40.0 

Diff. 

44-45 

44.00 

46.70 

44-51 

46.30 

47.6 

4.  Ser. 

— 

As  75.0 

Se  78.8  Br  79.97 

Rb854o 

Sr  87.6 

44-45 

45.60 

49.50 

46.80 

47.60 

40.5 

86 


THE  PERIODIC  LAW. 


It  is  clear  from  the  part  of  the  table  given  that  the 
idea  of  the  natural  families,  already  well  known,  was  the 
predominant  one,  and  that  the  numerical  order  of  the 
atomic  weights  was  subordinated  to  it.  Thus  the  four 
first  elements  form  a series  and  then  the  others  are  in 
sixes.  Some  elements  are  omitted  and  vacant  spaces 
are  left  in  other  cases.  In  the  fourth  series,  we  have  the 
first  member  omitted  in  order  that  analogous  elements 
may  fall  properly.  No  places  were  found  in  the  table 
for  copper,  silver  and  gold,  and  other  elements.  There 
is  certainly  less  evidence  of  periodicity  in  this  arrange- 
ment than  in  the  preceding  one  of  Newlands  and  yet 
underlying  the  system,  though  probably  unrecognized  or 
unappreciated  by  even  the  author  at  the  time  of  its 
publication,  are  the  two  great  principles  of  the  ascending 
series  of  atomic  weights  and  the  stated  recurrence  of 
elements  with  similar  properties.  It  was  Meyer’s  first 
attempt,  imperfect  and  incomplete,  but  sufficient  to  start 
that  brilliant  thinker  along  the  right  road  and  lead  him 
ultimately  to  the  great  discovery.  The  complete  table  of 
1864  will  be  given  later  on. 

68.  Hinrichs’  Deductions  from  the  Spectra  of  the  EIe= 
ments. — Following  up  his  hypothesis  of  one  primary  form 
of  matter,  first  announced  twelve  years  before,  Hinrichs 
called  the  recent  developments  in  spectroscopy  to  his  aid 
in  the  investigation.  Making  use  of  the  Plucker  and 
Ditsclieiner’s  determinations  of  the  wave  lengths  in 
various  spectra  of  the  metals,  he  drew  the  following  con- 
clusions (from  thirteen  elements  considered). 


THE  PANTOGEN  OF  HINRICHS. 


87 


“The  dark  lines  of  the  elements  are  equidistant 
throughout  the  spectrum,  but  of  varying  intensity,  many 
not  being  observed  (or  observable)  at  all ; the  intervals 
between  the  observable  lines  are  expressible  as  simple 
multiples  of  the  equal  distance  indicated  by  all.” 

Further,  by  considering  the  spectra  of  seven  elements, 
he  found  that  the  ‘ ‘ dark  lines  of  the  elements  are  related 
to  the  atomic  dimensions,  considering  the  elements  com- 
posed of  one  single  primary  element,  Urstoff.” 

He  concluded  by  promising  a series  of  articles  which 
should  show  that,  “ the  properties  of  the  chemical  elements 
are  functions  of  their  atoynic  weights,"  and  that,  “ the 
unity  of  matter  is  as  real  as  the  unity  of  force .” 

These  are  indeed  remarkable  statements,  coming  as 
they  do  three  years  before  Mendeleeff  announced,  in  his 
Periodic  Law  the  dependence  of  the  properties  upon  the 
atomic  weights,  and  almost  in  the  same  language. 

69.  The  Pantogen  of  Hinrichs. — This  theory,  Hinrichs 
states,  was  first  communicated  to  various  learned  men  and 
academies  of  Europe  in  1856  and  1857.  It  may  be  stated, 
beforehand,  that  Hinrichs  is  a believer  in  the  Proutian 
Hypothesis  as  extended  by  Marchand  and  Dumas. 
This  pantogen  is  the  constituent  of  the  various  elements. 
Atoms  of  pantogen  he  called  ‘ ‘pan  atoms.  ” It  is  necessary 
to  consider  them  as  material  points,  wuthout  any  hidden 
occult  property.  When  combined,  these  atoms  (all 
equal)  are  at  definite  distances.  Those  of  three  atoms 
form  a regulartriangle.  Chemical  elements  whose  atoms 
are  made  up  of  such  figures  are  called  Trigonoides 


88 


THE  PERIODIC  LAW. 


THE  PANTOGEN  OF  HINRICHS. 


(corresponding  to  non-metals.)  Four  panatoms  form  a 
square  and  elements  whose  atoms  are  composed  of  such 
figures  are  called  Tetragonoides  (metals).  Elements 
are  thus  classified  according  to  the  form  of  their  atoms. 
The  Trigonoides  and  Tetragonoides  form  the  true  orders 
of  the  elements.  These  orders  are  divided  into  families 
and  the  families  into  species  or  elements.  The  families 
can  be  expressed  by  an  algebraic  equation.  Thus  the 
“phosphoides”  will  be  Ph  = m (p).  These  are  the  ele- 
ments N,  P,  As,  Sb,  Bi.  In  the  equations  given,  p is  a 
regular  hexagon.  For  the  halogens,  or  as  they  are 
called  by  the  author,  “chloroides,”  the  equation  is  Ch= 
(I)-}-m.  p where  m=5. 

In  the  organic  series  (homologous)  he  saw  the  proto- 
types of  the  elements. 

His  chart  of  the  elements  is  here  reproduced.  The 
radii  in  this  mark  the  genera  and  the  spiral  cutting  them, 
according  to  the  order  number,  marks  the  elements,  the 
distance  of  the  species  from  the  centre  being  proportional 
to  its  atomic  weight.  as  the  symbol  of  pantogen,  is 
placed  at  the  centre  of  the  chart. 

It  is  evident  from  this  citation  from  Hinrich’s  Program 
der  Atomechanik  that  it  bears  little  relation  to  the 
Periodic  Taw.  The  author  states  in  a later  publication 
that  it  contains,  explicitly  stated,  all  that  is  true  in  the 
Periodic  Law.  He  is  a vigorous  critic  and  opponent  of 
this  law,  however,  and  may  mean  by  this  statement  that 
he  regards  very  little  of  it  as  true.  The  leading  facts  of 
his  system  seem  to  be  drawn  from  of  the  Proutian  Hy- 
pothesis of  the  composite  nature  of  the  elements  and  the 


90 


THE  PERIODIC  LAW. 


old  well-recognized  families,  falling  in  the  two  imper- 
fect divisions  of  non-metals  and  metals. 

The  diagram  which  he  gave  is  undoubtedly  the  pre- 
cursor of  the  spiral  arrangement  of  Baumhauer  and  others, 
although  the  fundamental  ideas  are  not  identical. 


CHAPTER  IV. 

THE  ANNOUNCEMENT  OF  THE  PERIODIC  DAW. 

1869-1871. 

70.  Periodic  Law. — We  come  now  to  the  period  of 
the  announcement  of  the  Periodic  Law.  The  numerical 
relations  already  given  form  an  important  part  of  the  Nat- 
ural Law  which  one  may  believe  will  in  time  be  recog- 
nized as  something  higher  and  broader  than  what  is  now 
known  as  the  Periodic  Law.  Some  of  these  regularities 
are  doubtless  fanciful,  the  importance  of  others  is  not 
yet  fully  understood  and  all  are  too  often  overlooked  in 
the  prominence  ascribed  to  the  ascending  series  of  atomic 
weights  and  their  regular  periodicity.  Much  credit  is 
due  to  the  early  investigators  who  worked  over  the 
strange  coincidences  and  connections  between  these 
important  physical  constants. 

71.  Mendeleeff’s  First  Paper. — The  first  paper  sum- 
ming up  all  the  more  important  principles  of  the  Peri- 
odic Law  was  one  laid  by  Mendeleeff  before  the  Russian 
Chemical  Society  in  March  1869.  (70.)  The  conclu- 
sions reached  in  that  paper  were  as  follows  : 

1.  The  elements,  if  arranged  according  to  their  atomic 
weights,  exhibit  an  evident  periodicity  of  properties. 

2.  Elements  which  are  similar  as  regards  their  chem- 
ical properties  have  atomic  weights  which  are  either  of 
nearly  the  same  value  ( e.g .,  platinum,  iridium,  osmium) 
or  which  increase  regularly  ( e.g . , potassium,  rubidium, 
caesium). 

3.  The  arrangement  of  the  elements,  or  groups  of  ele- 
ments, in  the  order  of  their  atomic  weights  corresponds 


92 


THE  PERIODIC  LAW. 


to  their  so-called  valences  as  well  as,  to  some  extent,  to 
their  distinctive  chemical  properties — as  is  apparent, 
among  other  series,  in  that  of  lithium,  beryllium,  barium, 
carbon,  nitrogen,  oxygen  and  iron. 

4.  The  elements  which  are  most  widely  diffused  have 
small  atomic  weights. 

5.  The  magnitude  of  the  atomic  weight  determines 
the  character  of  the  element  just  as  the  magnitude  of 
the  molecule  determines  the  character  of  a compound 
body. 

6.  We  must  expect  the  discovery  of  many  yet  unknown 
elements,  for  example,  elements  analogous  to  aluminium 
and  silicon,  whose  atomic  weight  would  be  between  65 
and  75. 

7.  The  atomic  weight  of  an  element  may  sometimes 
be  amended  by  a knowledge  of  those  of  the  contiguous 
elements.  Thus,  the  atomic  weight  of  tellurium  must 
lie  between  123  and  126,  and  cannot  be  128. 

8.  Certain  characteristic  properties  of  the  elements 
can  be  foretold  from  their  atomic  weights. 

“ The  aim  of  this  communication  will  be  fully  at- 
tained if  I succeed  in  drawing  the  attention  of  investi- 
gators to  those  relations  which  exist  between  the  atomic 
weights  of  dissimilar  elements  which,  as  far  as  I know, 
have  hitherto  been  almost  completely  neglected.  I 
believe  that  the  solution  of  some  of  the  most  important 
problems  of  our  science  lies  in  researches  of  this  kind.” 

The  chief  trouble  about  this  first  paper  of  Mendeleeff 
lay  in  the  imperfections  of  his  table,  which  is  here  given 
in  full.  The  arrangement  was  only  partially  according 


mendelTef’s  horizontal  table. 


93 


to  the  size  of  the  atomic  weights.  They  were  arranged 
in  vertical  series  and  some  of  the  atomic  weights  were 
incorrect. 


Mendeleeff’s  Table. 

1869. 

Ti 

50 

Zr 

90 

? 

180 

V 

5i 

Nb 

94 

Ta 

182 

Cr 

52 

Mo 

96 

W 

186 

Mn 

55 

Rb 

104.4 

Pt 

1974 

Fe 

56 

Ru 

104.4 

Ir 

198 

Ni,Co 

59 

Pd 

106.6 

Os 

199 

Cu 

634 

Ag 

108 

Hg 

200 

Be 

94 

Mg 

24 

Zn 

65.2 

Cd 

112 

B 

11 

A1 

27.4  ? 

68 

Ur 

116 

Au 

197 

C 

12 

Si 

28 

? 

70 

Sn 

118 

N 

14 

P 

3i 

As 

75 

Sb 

122 

Bi 

210 

O 

16 

S 

32 

Se 

794 

Te 

128? 

F 

19 

Cl 

35-5 

Br 

80 

I 

127 

Na 

23 

K 

39 

Rb 

854 

Cs 

133 

Tl 

204 

Ca 

40 

Sr 

87.6 

Ba 

137 

Pb 

207 

? 

45 

Ce 

92 

?Er 

56 

La 

94 

?Y 

60 

Di 

95 

Pin 

75-6 

Th 

118 

72.  Mendeleeff’s  Horizontal  Table. — Mendeleeff  used 
other  arrangements  of  the  elements  in  this  first  paper, 
one  of  which  has  been  generally  accepted  as  the  most 
convenient  mode  of  expressing  the  Periodic  Taw,  though 
the  vertical  rows  are  placed  horizontally  and  the  hori- 
zontal series  then  become  vertical. 


Li 

Na 

K 

Cu 

Rb 

Ag 

Ca 

Tl 

Be 

Mg 

Ca 

Zn 

Sr 

Cd 

Ba 

Pb 

B 

A1 

Ur 

Bi 

C 

Si 

Ti 

Zr 

Sn 

N 

P 

V 

As 

Nb 

Sb 

Ta 

0 

S 

Se 

Te 

W 

F 

Cl 

Br 

I 

. . 

94 


THE  PERIODIC  EAW. 


7 3-  Important  Features  of  the  System. — Mendeleeff 
also  brought  out  the  idea  that  all  the  elements  can  be  ar- 
ranged in  one  single  unbroken  series  made  up  of  consec- 
utive periods.  He  said  “ The  system  can  be  arranged 
in  the  form  of  a spiral  and  in  this  the  resemblances  prin- 
cipally appear  amongthe  members  of  every  other  series.” 

He  especially  emphasized  the  idea  of  periodicity.  He 
said  afterwards  (117):  ‘‘The  repetition  of  the  word  peri- 
odicity shows  that  from  the  very  beginning  I held  this  to 
be  the  fundamental  property  of  my  system  of  the  ele- 
ments.” 

In  his  paper  upon  atomic  volumes  a few  months  later, 
(71)  he  said  that  his  system  expressed  not  only  the 
chemical  relationship  of  the  elements  but  also  corres- 
ponded with  the  division  into  metals  and  non-metals, 
made  a distinction  between  the  valences,  brought  to- 
gether similar  elements  of  different  groups,  explained 
the  resemblance  of  the  series  of  the  elements  to  the 
homologous  groups,  set  aside  hydrogen  as  a typical  ele- 
ment, placed  near  together  those  elements  which  are 
most  widely  distributed  in  nature  and  which  accompany 
each  other,  showed  the  faultiness  of  Prout’s  hypothesis, 
and  pointed  out  the  relations  between  the  elements  con- 
formable to  their  reciprocal  affinities.  Lastly  he  pointed 
out  the  relations  existing  between  the  specific  gravities 
and  specific  volumes  of  the  different  series  of  elements, 
arranged  by  this  system. 

74.  Mendeleeff’s  Claim  as  a Discoverer. — As  to  his 

claims  as  a discoverer,  Mendeleeff  says  later,  very  truly, 
that  no  natural  law  is  discovered  all  at  once.  Many 


RECEPTION  ACCORDED  THE  DISCOVERY.  95 

might  claim  share  in  the  discovery  as  bringing  their 
contributions  of  fact  ortho  ught,  but  he  is  rightly  to  be 
regarded  as  the  discoverer  or  creator,  who  has  discerned 
not  only  the  philosophical  side  but  also  the  real,  and  who 
has  known  how  to  throw  such  light  upon  the  matter  that 
every  one  can  convince  himself  of  its  truth. 

He  stated  that  the  earlier  works  upon  the  numerical 
relations  of  the  atomic  weights  were  known  to  him,  ex- 
cepting those  of  de  Chancourtois  and  Newlands,  and 
that  he  was  principally  indebted  to  Rennsen  and  Dumas. 
“ I have  studied  their  researches  and  they  aroused  me 
to  seek  for  a true  law . ” ( 1 1 7 . ) 

In  the  elaboration  of  his  law  he  counted  Carnelley  as 
the  only  one  who  had  added  anything  new  to  it,  referring 
to  Carnelley ’s  work  upon  the  melting  points  and  mag- 
netic properties.  In  this  statement  he  considered  only 
that  which  had  been  done  up  to  1880.  As  to  Rothar 
Meyer,  he  denied  to  him  any  part  in  the  discovery  of 
this  law,  conceding  only  that  his  graphic  representation 
had  made  certain  properties  somewhat  clearer. 

75.  The  Reception  Accorded  the  Discovery. — It  was 
in  March  of  1869  that  Mendeleeff  announced  his  law  to 
the  Russian  Society.  In  August  he  presented  before 
the  Russian  Association  of  Naturalists  a paper  upon  the 
bearing  of  his  law  upon  the  volumes  of  simple  bodies. 
In  November  a further  paper  appeared  from  him  extend- 
ing the  application  of  the  new  system. 

Richter,  in  a letter  from  St.  Petersburg,  October  17, 
1869,(77)  mentioned  Mendeleeff’ s presentation  of  his  sys- 
tem before  the  Russian  Chemical  Society  and  added:  “ Ich 


96 


THE  PERIODIC  LAW. 


glaube  dass  diese  interessante  Formulirung  nicht  ver- 
fehlen  werde  Ihre  Aufmerksamkeit  zu  erregen.” 
While  it  is  perfectly  true  that  this  and  the  publication 
of  Meyer,  to  be  mentioned  next,  did  attract  attention, 
the  notice  given  them  was  not  at  all  in  accordance  with 
the  greatness  of  the  discovery.  It  is  evident  that  their 
importance  was  not  recognized  and,  it  may  be  added,  is 
not  fully  realized  even  yet.  So  far  as  can  be  judged  at 
present,  the  lecture  of  Dumas  at  Ipswich  created  a much 
greater  stir  among  chemists,  was  discussed  more  and  led 
more  immediately  to  others  undertaking  work  along  the 
same  or  similar  lines. 

76.  The  Evolution  of  Heyer’s  Table. — The  discussion 
between  Mendeleeff  and  Meyer  as  to  the  relative  merits 
of  their  claims  to  the  authorship  of  the  Periodic  Law  is 
one  of  longstanding  and  has  been  somewhat  hotly  waged 
by  the  principals  and  by  their  supporters. 

Meyer’s  claims  are  based  upon  his  table,  published  in 
1864  and  already  given.  Further,  something  less  than 
a year  after  Mendeleeff,  he  devised  a system  of  the 
elements  which  contained  the  principal  features  of  the 
Periodic  Law.  This  system  will  be  discussed  a little 
later  on.  Meyer  stated  that  it  was  an  expansion  of  his 
earlier  table  and  was  wTorked  out  in  entire  ignorance  of 
the  similar  work  of  Mendeleeff  which  had  appeared  in 
the  Russian  languagesomemonthspreviously.  Before  his 
article  was  published,  however,  he  saw  an  abstract  of 
Mendeleeff ’s  article  in  the  Zeitschrift  fur  Chemie  (N.  F. 
Bd.  V.  405.)  Such  being  the  state  of  the  case,  Meyer 
claims  credit  only  for  points  in  which  he  believed  he  had 


MEYER’S  TABLE  OF  1864. 


97 


improved  upon  the  table  of  Mendeleeff,  or  differed  from 
it.  In  his  original  article  he  said  that  his  table  was  es- 
sentially identical  with  the  one  given  by  Mendeleeff. 

77.  Meyer’s  Table  of  i864. — For  purposes  of  comparison 
Meyer’s  first  table  is  here  given  in  its  complete  form. 
It  will  be  observed  that  there  are  two  portions.  One  of 
twenty-eight  elements  in  six  vertical  rows  and  a second 
of  sixteen  in  five  rows.  There  is  a manifest  struggle  be- 
tween the  desire  to  arrange  the  elements  according  to 
the  atomic  weights  and  at  the  same  time  to  have  them 
fall  according  to  their  analogies  in  families.  It  is  well 
to  note  the  significance  attached  to  the  difference-num- 
bers, a signifiance  not  yet  understood  nor  appreciated. 


Meyer’s  First 

Table. 

1864. 

4 val. 

3 val. 

2 val. 

1 val. 

1 val. 

2 val. 

— 

Li  7.03 

(Be  9.3) 

Diff.  .... 

— 

16.02 

(14-7) 

C 12.0 

N 14.4 

O 16.00 

F 19.0 

Na  23.5 

Mg  24.0 

Diff.  16.5 

16.96 

16.07 

16.46 

16.08 

16.0 

Si  28.5 

p 31.0 

S 32.0 

Cl  35-46 

K 39.13 

Ca  40.0 

Diff.  -ip- 44' 45 

44.0 

46.7 

44-51 

46.3 

47.0 

As  75.0 

Se  78.8 

Br  79.97 

Rb  85.4 

Sr  87.0 

Diff.  44-55 

45-6 

49-5 

46.8 

47.6 

49.0 

Sn  117.6 

Sb  120.6 

Te  128.3 

1 126.8 

Cs  133.0 

Diff.  ^F-44-7 

-2—43-7 

— 

— 

35-5 

Pb  207.0 

Bi  208.0 

— 

(T1  204.0?) 

Ba  137. 1 

4 val. 

4 val. 

4 val. 

2 val. 

1 val. 

f Mn  55.1 
l Fe  56.0 

Ni  58.7 

Co  58.7 

Zn  65.0 

Cu  63.5 

f 49.2 

Diff  4 

45-6 

47-3 

46.9 

44-4 

(48.3 

Ru  104.3 

Rh  104.3 

Pd  106.0 

Cd  hi. 9 

Ag  107.94 

Diff.  -f—  46.0 

46.4 

¥ 46.5 

Hr1  44-5 

44-4 

Pt  197.1 

Ir  197. 1 

Os  199.0  Hg  200.2 

Au  196.7 

98 


THE  PERIODIC  LAW. 


78.  rieyer’s  Table  of  1868. — Lately  Seubert,  the  pupil 
and  friend  of  Meyer,  has  published  an  account  (239) 
of  a paper  which  has  come  to  light  since  the  death  of 
its  distinguished  author  and  which  shows  the  indepen- 
dence of  Meyer  in  his  work.  This  was  a preliminary 
suggestion  of  his  System,  an  elaboration  of  his  work  of 
1864,  written  out  and  handed  to  his  friend  and  successor 
in  the  chair  of  chemistry  at  Eberswald,  Professor  A. 
Remele,  in  July  1868.  Meyer  first  learned  of  its  pre- 
servation when  Remele  showed  it  to  him  in  1893  after 
his  lecture  before  the  German  Chemical  Society  upon 
the  Periodic  Law.  He  then  expressed  regret  that  he 
had  not  published  it  in  1868,  even  though  incomplete. 
This  table  is  fuller  and  shows  many  differences  from  the 
earlier  one.  Fifty-two  elements  are  given  and  in  fifteen 
vertical  rows.  There  are  many  imperfections  in  it. 
Thus  there  is  no  place  for  boron  in  it  and  aluminium  is 
put  down  twice  because  of  evident  doubt  as  to  its  proper 
location.  Even  then  its  proper  place  is  missed.  Imper- 
fectly known  atomic  weights  also  cause  some  trouble  in 
the  arrangement.  Every  one  must  admit  that  there  is 
a wide  step  between  this  table  and  the  one  given  by 
Meyer  after  the  publication  of  Mendeleeff. 


MEYER’S  TABLE  OF  1868 


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Suggestion  for  a System  of  Elements  by  Lothar  Meyer.  Summer  1868. 


IOO 


THE  PERIODIC  LAW. 


79.  Heyer’s  Table  of  1870. — Eothar  Meyer’s  article 
upon  the  “ Nature  of  the  Elements  as  Functions  of  their 
Atomic  Weights”  (81)  appeared  in  the  year  1870, 
although  written,  as  he  says,  in  December  1869.  The 
table  there  given  is  an  expansion  (116)  of  his 
table  published  in  1864.  It  is  distinguished  from  it 

in  that  the  consecutive  atomic  weights  are  not  arranged 
horizontally  but  vertically  as  in  one  of  the  tables  of 
Mendeleeff.  He  had  tried  to  arrange  all  the  elements 
in  that  first  table  but  had  been  unable  to  do  so  because 
of  the  numerous  erroneous  atomic  weights.  When  these 
were  corrected  he  saw  the  possibility  of  arranging  all  of 
the  elements  into  one  table  in  accordance  with  the  size 
of  the  atomic  weights.  Although  Mendeleeff  did  say 
that  the  weights  might  be  ordered  in  one  single  spiral, 
he  did  not  do  this  and  could  not  have  attached  much  im- 
portance to  such  an  arrangement.  In  fact  it  was  not 
possible  to  so  arrange  them  with  the  series  as  first  given 
by  him  and  with  the  false  atomic  weights  included  in 
his  table.  Meyer  observed,  (116)  ‘‘had  Mende- 
leeff then  attached  any  importance  to  the  formation  of 
a single  series  he  would  have,  without  doubt,  chosen 
other  values  for  these  elements.  Mendeleeff  did  not 
hesitate  to  ‘‘correct”  the  value  of  the  atomic  weights  b5^ 
his  table  and  to  insert  unknown  ones  when  necessary.” 
A close  examination  of  Mendeleeff’s  first  table  will  show 
a struggle  between  a desire  to  have  a single  series  ac- 
cording to  atomic  weights  and  still  to  get  the  analogous 
elements  to  fall  into  periods.  The  regular  recurrence  of 
the  periods  is  brought  out  better  by  Newlands  in  his 


MENDELFIEFF’S  TABLE  OF  1871.  IOI 

scheme  though  Newlands  had  more  inaccuracies  of 
atomic  weights  to  contend  with  and  less  knowledge  of 
the  analogies  between  the  elements.  Meyer’s  table  is 
much  clearer  than  that  of  Mendeleeff  and  brings  out 
the  series  of  analogous  elements  better.  It  is  given  on 
page  102. 

One  claim  made  by  Mejmr  for  this  table,  is  the  dis- 
covery of  what  he  called  double  periodicity.  This  is 
shown  in  the  table  where  we  see  that  elements  of  analo- 
gous properties  recur  in  every  other  column  and  not  in 
the  immediately  adjacent  ones,  thus  giving  two  series  of 
analogous  bodies.  As  has  been  alread}'  shown  by  the 
quotation  from  Mendeleeff ’s  first  article  the  two  rec- 
ognized that  the  analogy  was  apparent  principally  be- 
tween the  members  of  every  other  series.  These  he 
distinguished  later  as  the  ‘ ‘ matched  and  unmatched’  ’ 
series. 

80.  Mendeleeff’s  Table  of  1871. — Mendeleeff’s  table 
given  in  1871  (74)  was  a great  improvement  over  his 
first.  He  gave  in  fact  two  tables,  one  giving  the  hori- 
zontal and  the  other  the  vertical  mode  of  arrangement. 
These  tables  follow  on  pages  103  and  104. 


102 


THE  PERIODIC  LAW. 


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Mendex&JKF’s  Table  I. — 1871. 


104 


THE  PERIODIC  DAW. 


Mendeeeeff’s  Tabee  II. 


Gr.  Ser.  I. 

2. 

4- 

6. 

8. 

10. 

12. 

I. 

Li  7 

K 39 

Rb  85 

Cs  133 

IO 

II 

Be  9.2 

Ca  40 

Sr  87 

Ba  137 

III. 

B 11 

? Sc 

Yt  89? 

Di  139? 

Er  175? 

IV. 

C 12 

Ti  48 

Zr  90 

Ce  141 

La  180? 

Th  231 

V. 

N 14 

v 51 

Nb  94 

? 2 

Ta  182 

VI. 

O16 

Cr  52.5 

Mo  96 

? 

W 184 

Ur  240 

VII. 

F 19 

Mn  55 

VIII 

Fe  56 

Ru  103 

Os  194 

— 

Co  58.6 

Rh  104 

Ir  195 

Ni  58.6 

Pd  106 

•• 

Pt  197 

I.  H 1 

Na  23 

Cu  63.5 

Ag  108 

Au  197 

II. 

Mg  24 

Zn  65 

Cd  112 

3 

Hg  200 

III. 

A1  27.3 

Ga  69 

In  113 

.. 

Tl  204 

IV. 

Si  28 

??? 

Sn  1 18 

Pb  204 

V. 

P 31 

As  75 

Sb  120 

Bi  208 

VI. 

S 32 

Se  79 

Te  125  ? 

.... 

— 

VII. 

Cl  35-5 

Br  80 

I 127 

.. 

— 

— 

In  a foot  note  it  was  stated  that  possibly  Di  had  an  atomic 
weight  of  146  and  would  occupy  place  marked  2.  In 
another  note  he  spoke  of  Carnelley’s  having  assigned 
Norwegium  to  place  3.  These  tables  contain  the  Peri- 
odic Law  as  it  is  known  to  us.  They  have  not  been 
very  materially  altered,  though  they  have  been  corrected 
in  minor  points.  The  work  since  has  been  mainly  one 
of  elaboration.  The  credit  for  the  expansion  and  filling 
out  of  the  Periodic  Law,  its  extension  to  the  other  proper- 
ties of  the  elements  and  the  bringing  of  the  various  com- 
pounds of  these  elements  into  consideration  also,  has 
been  almost  entirely  due  to  the  skill  and  knowledge  of 
Mendeleeff.  He  was  bold  and  successful  in  his  proph- 
ecy of  new  elements  and  their  properties,  and  also  as  to 


MEYER’S  EATER  TABLES. 


105 


changes  in  properties  then  generally  accepted.  Many, 
though  not  all,  of  these  prophecies  have  been  fulfilled. 

81.  fleyer’s  Later  Tables. — Lothar  Meyer,  in  the 
later  editions  of  his  “ Modern  Theories  of  Chemistry” 
has  given  his  table  in  a changed  and  improved  form. 
He  says  of  this  table  (3d  ed.  p 292): 

“ If  one  will  think  of  this  table  as  rolled  upon  an  up- 
right cylinder  so  that  the  right  side  shall  touch  the  left, 
thus  nickel  joining  itself  directly  to  copper,  palladium  to 
silver  and  platinum  to  gold,  one  will  get  as  is  easy  to  be 
seen,  a continuous  series  of  all  the  elements  arranged 
in  the  form  of  a spiral  and  according  to  the  size  of  the 
atomic  weights.  The  elements  which  by  this  arrange- 
ment stand  over  one  another  form  a natural  group,  or 
family,  the  members  of  which  resemble  each  other  in 
very  unequal  measure.  In  most  of  the  groups  four  or 
five  of  the  seven  or  eight  members  are  more  nearly  re- 
lated to  one  another  than  to  the  remaining  three  which 
again  show  a great  similarity  to  one  another.  In  the 
second  vertical  column,  beginning  with  Li,  the  five  light 
alkali  metals  are  very  much  alike,  while  the  three  heavy 
metals  agree  with  one  another  in  many  properties;  with 
alkali  metals,  however,  only  in  single  points,  as  in  the 
isomorphism  of  many  of  the  compounds  and  in  their 
ability  to  unite  with  a single  atom  of  a halogen. 


I. 


Li 

7-oi 

15.98 


Na 

22.99 

16.04 


K 

39  -°3 
24-15 


Cu 

63-  r8 
22.0 


Rb 

85-2 

22-5 


Ag 

107.66 

25.0 


Cs 

132-7 


165 

Au 

196-2 


222 


II. 


Be 

9.08 


14.86 


Mg 

23-94 


15-97 


Ca 

39-91 


24.97 


Zn 

64-88 

22.4 


Sr 

87-3 

24.4 


Cd 

III  .7 

25.2 

Ba 

136.86 

? 

170 

Hg 

199.8 


226 


III. 

B 

10-9 

16.14 

A1 

27.04 

16.93 

Sc 

43-97 

25-9 

Ga 

69.9 

19.7 

? Y 
89.6 

23.8 

In 

113*4 

25-1 

La 

I38-5 

Yb 

172.6 

T1 

203.7 

? 

230 

IV. 


C 

11-97 


l6 

Si 

28 

20 

Ti 

48 

24 

(Ge) 

72 

18 

Zr 

9°. 4 

27.4 

Sn 

H7-35 

23-8 

Ce 

141  -2 

? 

I76 

Pb 

206.39 

? Th 
231.96 

V. 

N 

I4.OI 

16.95 

p 

30.96 

20.1 

V 

51  • 1 

23.8 

As 

74-9 

18.8 

Nb 

93-7 

25-9 

Sb 

119-6 

25 

Di 

145 

Ta 

182 

Bi 

207.5 

? 

234 

VI. 

O 

15.96 

16.02 

s 

31.98 

20.47 

Cr 

52-45 

26.48 

Se 

78.87 

17.0 

Mo 

95*9 

3°-4 

Te 

126.3 

25 

? 

151 

w 

183.6 

? 

210 

?4 

239.8 

VII. 

F 

19.06 

16.31 

Cl 

35-37 

19.4 

Mn 

54-8 

25.0 

Br 

79.76 

19 

? 

99 

28 

1 

126.54 

25 

? 

152 

185 

? 

211 

Fe 

55-86 

Co 

58.6 

Ni 

58.6 

Ru 

103-5 

Rh 
104. 1 

Pd 

106.2 

Os. 

195? 

Ir 

I92-5 

Pt 

194-3 

TARDY  RECOGNITION  OF  THE  LAW.  107 

In  a similar  manner  each  of  the  following  columns  can 
be  separated  into  two  groups,  clearly  different  and  yet 
related  to  one  another  in  certain  particulars.” 

82.  rieyer’s  Curve  of  the  Atomic  Volumes. — Meyer 
was  the  first  to  give  a graphic  representation  of  this  law. 
He  devised  a curve  intended  to  show  the  dependence  of 
the  atomic  volumes  upon  the  atomic  weights.  The 
atomic  weights  were  taken  as  the  abscissae,  the  atomic 
volumes  forming  the  ordinates.  The  curve  uniting  the 
tops  of  these  ordinates  gave  a picture  of  the  changes 
which  the  atomic  volume  experiences  with  increasing 
atomic  weight. 

83.  The  Failure  to  Recognize  the  Importance  of  the 
Law. — As  has  been  said,  the  Periodic  Law  soon  attracted 
attention,  but  its  importance  does  not  seem  to  have  been 
generally  recognized  at  first,  nor  was  it  widely  accepted 
as  a law.  In  fact  for  several  years  it  nearly  dropped  out 
of  sight  and  it  was  only  the  lucky  discovery  of  some 
new  elements,  thus  fulfilling  certain  predictions  of  Mende- 
leeff,  that  brought  it  prominently  before  the  chemical 
world.  How  long  it  would  otherwise  have  laid  unnoticed 
can  only  be  guessed  at. 

In  1879,  the  London  Chemical  News  translated  from 
the  Moniteur  Scientifique  and  republished  Mendeleef’s 
article  on  the  “ Periodic  Law  of  the  Chemical  Ele- 
ments,” because  ‘‘considerable  attention  has  been 
drawn  to  M.  Mendeleeff’s  memoir  in  consequence  of  the 
newly  discovered  elements,  gallium  and  scandium,  being 
nearly  identical  with  the  predicted  elements  eka-alumi- 
nium  and  eka-boron.” 


io8 


the  periodic  raw, 


of  Atomic  Volumes  e*  L Meyer 


TARDY  RECOGNITION  OF  THE  LAW.  109 

Mendeleeffsaid  in  his  introductory  note  to  the  article 
mentioned : 

“Although  seven  years  have  passed  since  these 
thoughts  absorbed  my  attention  ; although  other  occu- 
pations have  withdrawn  my  attention  from  the  problem 
of  the  elements  which  was  always  getting  nearer  solu- 
tion ; in  short,  although  I might  wish  to  put  this  ques- 
tion otherwise  than  I did  seven  years  ago,  still  I keep  to 
the  same  firm  conviction  that  I formerly  had  on  the  im- 
portance and  value  of  the  theorems  on  which  my  memoir 
is  based.  Several  occurrences  have  aided  to  make  some 
of  the  logical  consequences  of  the  Periodic  haw  popular. 

1st.  The  law  I announced  has  been  considered  as  a 
repetition  in  another  form  of  what  has  been  already  said 
by  others.  It  is  now  certain  that  the  Periodic  Law 
offers  consequences  that  the  old  systems  had  scarcely 
ventured  to  foresee.  Formerly  it  was  only  a grouping, 
a scheme,  a subordination  to  a given  fact  ; while  the 
Periodic  Law  furnishes  the  facts  and  tends  to  strengthen 
the  philosophic  question  which  brings  to  light  the  mys- 
terious nature  of  the  elements.  This  tendency  is  of  the 
same  category  as  Prout’s  Law,  with  the  essential  differ- 
ence that  Prout’s  Law  is  arithmetical  and  that  the  Peri- 
odic Law  exhausts  itself  in  connecting  the  mechanical 
and  philosophical  laws  which  form  the  character  and 
glory  of  the  exact  science.  It  proclaims  loudly  that  the 
nature  of  the  elements  depends  above  all  on  their  mass, 
and  it  considers  this  function  as  periodic.  The  formula 
of  the  law  might  be  changed  ; a greater  appreciation  of 
this  function  will  be  found,  but  I believe  that  the  origi- 
nal idea  of  the  periodic  law  will  remain.” 


I IO 


THE  PERIODIC  LAW. 


It  is  undoubtedly  true,  as  has  been  said,  “the  dis- 
covery of  gallium  may  be  considered  as  the  inaugura- 
tion of  the  Periodic  Law.’’ 

84.  The  Criticism  of  Berthelot. — From  what  has  been 
said,  it  will  be  seen  that  one  must  look  into  the  second 
decade  after  the  announcement  of  the  law  for  criticisms 
of  it.  Some  of  these  may  be  quoted  as  showing  the 
character  of  the  reception  accorded  it. 

An  adverse  criticism  from  Berthelot  will  first  be  given. 
The  French  have  been  especially  slow  in  acknowledging 
the  merits  of  the  discovery.  Somewhat  strangely  Ber- 
thelot’s  critique  is  placed  in  his  Origins  of  Alchemy  ( 145) 
where  one  would  scarcely  look  for  anything  of  that 
character,  and  so  has  escaped  more  general  notice. 

“It  is  known  that  certain  general  relations  exist  be- 
tween the  atomic  weights  of  the  bodies,  their  atomic 
volumes  and  their  different  physical  and  chemical 
properties.  These  relations  were  studied  long  before 
the  arrangement  of  the  elements  in  parallel  series. 
They  result  from  the  absolute  atomic  wreights  and  not 
from  any  periodic  differences.  Yet,  as  these  relations  are 
the  immediate  consequence  of  the  atomic  weights,  the 
coincidences  established  between  these  come  to  light 
again  necessarily  when  we  consider  their  atomic  volumes 
and  all  the  other  correlative  properties  of  the  chemical 
mass  of  the  elements. 

“ This  circumstance  increases  the  convenience  of  the 
new  table.  It  brings  no  new  proof  of  the  existence  of 
the  periodic  series.  It  is  necessary  to  guard  against  all 
illusion  in  that  direction.  Let  us  examine  the  predic- 


THE  CRITICISM  OF  BERTHELOT. 


1 1 1 


tions  deduced  from  the  new  classification.  It  is  in  this  re- 
spect more  than  in  any  other  that  the  system  should  prove 
interesting.  In  the  arithmetical  progressions  which  em- 
brace each  family  of  elements,  it  is  seen  that  certain 
terms  are  lacking.  Between  S=  32  and  Se  = 79  there 
should  exist  two  intermediate  terms  48  and  64.  In  the 
same  way  between  Se  = 79  and  Te=  128,  two  terms  are 
lacking,  96  and  112.  Evidently  these  are  to  be  filled  in 
by  unknown  elements  and  there  is  an  opening  here  for 
research.  But  as  the  number  of  these  is  too  great,  the 
authors  of  the  system,  in  haste  to  fill  the  gaps  in  each 
family,  have  interpolated  elements  already  known  which 
are  manifestly  strangers  to  the  family  : such  as  Mo  in- 
serted between  Se  and  Te  : W and  U added  in  like  man- 
ner to  the  series.  To  the  series  of  Ei=7,  H=i  has 
been  placed  at  the  head  and  at  the  end  Cu  =63,  Ag  = 108 
and  Au  = 197.  All  this  trenches  upon  the  fanciful. 

“ In  the  same  way  between  Cl  and  Br  and  between  Br 
and  I certain  terms  of  the  arithmetical  progression  are 
lacking.  Here  we  have  again  hypothetical  and  to-be- 
discovered  elements.  Notice  here  that  their  properties 
are  not  undetermined.  In  fact  the  physical  or  chemical 
properties  of  an  unknown  element  can  be  predicted  and 
calculated  when  its  atomic  weight  and  family  or  analo- 
gies are  given.  This  prediction  is  not  a consequence  of 
the  theory  of  the  periodic  series.  It  results  purely  and 
simply,  from  the  long-known  laws  and  analogies  which 
are  independent  of  the  new  system. 

“It  is  impossible  not  to  draw  the  attention  of  the  critic 
and  of  the  philosopher  to  the  convenient  trick,  by  the  aid 


1 1 2 


THE  PERIODIC  LAW. 


of  which  the  authors  of  the  system  have  managed  to  in- 
clude not  only  all  known  but  all  possible  substances. 
This  trick  consists  in  forming  their  table  writh  terms 
which  do  not  differ  by  more  than  two  units,  terms  so 
bound  together  that  no  new  bod}7,  wdiatever  it  may  be, 
can  fall  outside  the  meshes  of  the  net.  The  thing  is  the 
more  assured  since  the  periodic  differences  often  admit 
in  their  applications  to  known  atomic  weights,  of  varia- 
tions of  one  to  two  units.  We  see  that  it  is  no  longer  a 
question  of  fractions  of  units  which  separate  the  multiples 
of  hydrogen  such  as  were  raised  as  objections  to  the  hy- 
pothesis of  Prout  and  Dumas. 

“ Without  excluding  absolutely  the  conception  of 
parallels,  we  must  avoid  attaching  too  high  a scientific 
value  to  frames  so  elastic.  Especially  must  we  guard 
against  attributing  to  it  discoveries,  past  or  future,  to 
which  it  does  not  necessarily  conduce  in  a precise  and 
necessary  manner.  We  might  say,  with  all  sincerity, 
that  outside  of  the  old  natural  families  of  the  elements, 
known  for  a long  time,  there  is  little  here  but  artificial 
groupings.  The  system  of  the  periodic  series  has  not, 
any  more  than  the  system  of  the  multiples  of  hydrogen, 
furnished,  up  to  the  present,  a certain  and  definite  rule 
for  discovering  either  the  simple  bodies  found  in  late 
years  or  those  which  we  do  not  yet  know.  None  of  these 
systems  has  given  a positive  method  of  fore-seeing,  much 
less  of  synthetically  forming,  our  elements. 

“It  is  not  that  such  systems  have  no  use  in  the  sci- 
ence ; they  serve  to  arouse  and  sustain  the  imagination 
of  investigators.  They  submit,  with  difficulty,  to  rest 


THE  CRITICISM  OF  BERTHEEOT. 


”3 


upon  a purely  experimental  basis  and  push  into  the 
region  of  construction  and  of  theories  that  spring  from  the 
desire  for  unity  and  causality  inherent  in  the  human 
mind.  It  would  be  too  harsh,  and  useless  besides,  to 
wish  to  prescribe  everything  tentative  of  this  nature. 
But  such  is  the  seduction  exercised  by  these  dreams,  that 
it  is  necessary  to  guard  against  seeing  in  them  the  fun- 
damental laws  of  our  science  and  the  basis  of  its  facts, 
under  pain  of  falling  again  into  a mystic  enthusiasm 
parallel  to  that  of  the  alchemist. 

“ Such  conceptions  are  on  the  one  hand  too  narrow 
and  it  thus  invites  to  elevating  them  too  high.  At  bottom, 
those  who  invoke  the  multiples  of  hydrogen  and  the  per- 
iodic series,  bind  everything  to  the  conception  of  certain 
atoms  smaller  than  those  of  the  reputedly  simple  bodies. 
But  if  it  comes  to  demonstrating  that  the  equivalents  of 
the  actual  elements  are  rigorously  multiples,  the  one  of 
the  other,  or  more  generally,  multiples  of  certain  num- 
bers, forming  the  differences  in  determined  arithmetical 
progressions,  it  results  in  this  probable  conclusion,  that 
the  actually  simple  bodies  represent  the  unequal  stages 
of  condensation  of  the  same  fundamental  material.  This 
fashion  of  conceiving  things  has  nothing  which  can  be 
repugnant  to  a chemist  versed  in  the  history  of  his 
science. 

“ One  can  call  to  mind,  as  proofs,  facts  well-known  to 
all  and  which  are  not  without  some  analogy.  Such  are 
the  multiple  forms  of  carbon,  an  element  which  mani- 
fests itself  in  the  free  state  in  the  most  diverse  forms  and 
which  gives  rise  to  many  series  of  compounds  corres- 


THE  PERIODIC  LAW. 


114 

ponding  in  a certain  manner  with  each  of  these  funda- 
mental forms,  as  the  compounds  of  an  ordinary  element 
correspond  with  that  element.  Carbon  represents,  in 
some  sort,  the  common  generator  of  an  entire  family  of 
elements,  differing  in  their  condensation.  One  is 
brought  to  the  same  conclusion  by  a study  of  the  hydro- 
carbons. The  objection  might  be  raised  that  the  diver- 
sity of  the  properties  of  carbon  should  not  be  less  than 
the  diversity  existing  between  the  elements  comprised 
in  one  family,  those  of  the  halogens  or  of  the  sulphur 
group,  for  instance.  In  reality  S and  Se  never  produce 
the  same  compounds  in  uniting  -with  O,  H,  or  N,  and 
they  cannot  be  regenerated  by  condensation  of  the  most 
simple  among  them. 

“ To  sum  up,  carbon  viewed  in  its  different  states  and 
degrees  of  condensation  is  equivalent  in  itself  to  an  en- 
tire class  of  simple  bodies.  O,  S,  Se,  and  Te  by  the 
same  reasoning  could  represent  the  different  states  of  a 
common  element.  Further,  ozone,  a body  of  very  sim- 
ple properties,  and  comparable  therefore  to  a true  ele- 
ment, has  been  really  formed  of  oxygen,  its  existence 
to  a certain  extent  justifying  the  preceding  conjectures. 

85.  Mendeleeff’s  Reply. — It  is  best  to  quote  here, 
from  his  Faraday  lecture,  ( 1 8 1 ) Mendeleeff’s  reply  to 
this  criticism  of  Berthelot.  This  also  gives  the  author’s 
views  of  the  many  attempts  to  make  use  of  the  Periodic 
L,aw  in  speculations  concerning  the  original  form  or 
forms  of  matter.  We  shall  come  across  many  such 
speculations  in  the  remaining  pages  of  this  work. 

“ Feeling  that  spectrum  analysis  will  not  yield  a sup- 


ostwald’s  criticism. 


115 

port  to  the  Pythagorean  conception,  its  modern  promo- 
ters are  bent  upon  its  being  confirmed  by  the  Periodic 
Law.  It  is  evident  that  the  illustrious  Berthelot  has 
simply  mixed  up  the  fundamental  idea  of  the  Law  of 
Periodicity  with  the  ideas  of  Prout,  the  alchemist,  and 
Democritus  about  primary  matter.  But  the  Periodic 
Law,  based  as  it  is  on  the  solid  and  wholesome  ground 
of  experimental  research,  has  been  evolved  indepen- 
dently of  any  conception  as  to  the  nature  of  the  elements; 
it  does  not  in  the  least  originate  in  the  idea  of  an  unique 
matter ; and  it  has  no  historical  connection  with  that 
relic  of  the  torments  of  classical  thought,  and  therefore 
it  affords  no  more  indication  of  the  unity  of  matter  or  of 
the  compound  character  of  our  elements  than  the  Law 
of  Avogadro,  or  the  Law  of  Specific  Heats,  or  even  the 
conclusions  of  spectrum  analysis.  None  of  the  advo- 
cates of  an  unique  matter  have  ever  tried  to  explain  the 
law  from  the  standpoint  of  ideas  taken  from  a remote 
antiquity  when  it  was  found  convenient  to  admit  the  ex- 
istence of  many  gods  or  of  an  unique  matter.” 

86.  Ostwald’s  Criticism. — Ostwald  has  the  following 
criticism  of  the  Periodic  Law  on  pages  126  and  127  of 
his  Lehrbuch  der  Allgemeinen  Chemie  (149). 

“ The  numerous  and  unexpected  developments  which 
the  Periodic  Law  has  given  us  as  to  the  relations  of  the 
atoms,  one  to  another,  should  not  make  us  blind  to  cer- 
tain difficulties  which  have  arisen  in  its  full  application. 
Thus  the  discussion  over  the  atomic  weight  of  beryllium 
is  not  yet  closed,  since  there  are  many  reasons  for  not 
accepting  the  arrangement  of  the  elements  as  given. 


THE  PERIODIC  LAW. 


1 16 

Again  elements  are  separated  from  one  another  which 
in  the  form  of  their  compounds  stand  close  together — as 
mercury  and  copper,  with  which  it  has  more  points  of 
resemblance  than  with  zinc  and  cadmium.  Sodium  is 
separated  from  the  alkaline  metals  proper  and  placed 
with  copper,  silver,  and  gold.  The  silver  here  shows, 
at  best,  a relationship  through  the  isomorphism  of  the 
water-free  sulphate.  Also  the  oxidation  steps  held  up 
by  Mendeleeff  as  characteristic  or  typical  are  neither  the 
only  ones,  nor  the  lowest,  nor  yet  the  highest,  indeed  they 
are  often  unknown  and  incapable  of  existence. 

“These  objections  are  not  raised  to  refute  the  Periodic 
Law.  They  are  too  few  in  number  for  that  and  stand 
opposed  to  too  many  favoring  circumstances.  They 
serve  only  to  show  that  the  law  in  its  present  form  is 
only  the  beginning  of  a most  promising  line  of  thought. 
The  idea  of  the  analogy  of  the  elements  has  still  too 
much  undetermined  to  permit  of  its  definite  use.  There 
is  still  no  numerical  expression  for  it.  Further,  the  rela- 
tion of  multiple  proportions  to  the  Periodic  Law  remains 
to  be  examined.  Mendeleeff  shows  justly  that  the 
views  predominating  at  present  as  to  the  valence  of  the 
elementary  atoms  has  real  meaning  only  for  the  carbon 
compounds  and  falls  into  constant  contradiction  in  the 
case  of  the  inorganic  compounds.  It  is  to  be  hoped  that 
a theory  of  chemical  compounds  which  wall  suit  both 
branches  of  chemistry  will  be  developed  out  of  the  rela- 
tions of  the  multiple  proportions  to  the  Periodic  Law. 
Lastly,  it  cannot  be  left  without  mention  that  in  reflect- 
ing upon  the  causes  of  the  Periodic  Law  the  same  meta- 


ostwald’s  criticism. 


117 


physical  consequences  press  forward  which  have  served 
as  starting  points  for  the  hypothesis  of  Prout  and  have 
been  somewhat  supported  by  the  approximate  and  par- 
tial agreement  of  the  same  with  experiment.  If  the 
properties  of  the  elements  prove  to  be  functions  of  the 
atomic  weights,  the  thought  lies  near  to  seek  in  these 
also  the  causes  of  the  same,  and  the  assumption  of  a 
primal  matter,  whose  different  states  of  condensa- 
tion define  the  differences  of  the  elements,  can  hardly  be 
set  aside.  These  hypotheses  are  far  reaching  and  far 
removed  from  sure  foundation,  but  they  accord  with  the 
general  tendency  of  natural  science.” 


CHAPTER  V. 


DEVELOPMENT  OF  THE  SYSTEMS, 

1870-1880. 

In  the  preceding  chapter  it  was  stated  that  but  little 
was  done  to  improve  and  extend  the  Periodic  Law  dur- 
ing the  first  years  after  its  announcement.  Its  discoverers 
had  dropped  it  for  other  work,  Mendeleeff  finding  occu- 
pation in  the  study  of  the  origin  of  petroleum  and  in 
various  physico-chemical  researches.  Meyer  (91) 
complained  of  the  ‘ ‘ present  lack  of  system  in  in- 
organic chemistry  ” and  appeals  for  the  putting  forth  of 
greater  efforts  in  the  development  of  this  branch  of  chem- 
istry. He  mentioned  “the  natural  system  of  the  ele- 
ments arranged  according  to  their  atomic  weights  with 
which  he  and  Mendeleeff  had  been  busying  themselves  of 
late  years”  as  a step  towards  this  development.  The 
natural  system  should  be  the  principle  of  the  classifica- 
tion of  inorganic  compounds. 

87.  A Return  to  Numerical  Regularities. — We  will 
find  in  the  record  of  this  decade,  therefore,  chiefly 
independent  and  new  systems  and  a recurrence  of 
numerical  regularities  such  as  were  pointed  out  almost 
ad  nauseam  in  the  period  immediately  following  the  lec- 
ture of  Dumas.  It  is  strange  to  see  how  indefatigable 
chemists  have  been  along  this  line  and  how  many  differ- 
ent “relations”  they  have  discovered  between  the  six- 
ty odd  numbers  lying  in  the  range  of  atomic  weights 
between  one  and  two  hundred  and  forty. 


120 


THE  PERIODIC  LAW. 


There  seems  from  now  on  a more  marked  tendency 
toward  the  search  after  laws  underlying  these  relations.  In 
the  earlier  periods  the  discovery  of  isolated  “regulari- 
ties ’ ’ seemed  to  satisfy  the  investigator. 

88.  Growth  in  the  Belief  of  the  Unity  of  Matter. — 

There  is  also  from  this  time  forward  a very  evident 
increase  in  the  number  of  adherents  to  the  philosophic 
theory  of  the  Unity  of  Matter.  There  is  a revival  of  the 
Proutian  Hypothesis  under  various  forms.  The  com- 
posite nature  of  the  elements  is  more  widely  and  boldly 
stated  and  discussed.  The  last  question  of  the  century 
shows  a revulsion  to  this  old  hypothesis  in  so  far  as  it 
teaches  that  the  elements  are  compound,  though  the 
part  of  it  referring  to  the  multiple  relations  existing  be- 
tween the  atomic  weights  has  been  largely  set  aside. 

89.  Baumhauer’s  Spiral  Arrangement. — In  the  year 
1870,  shortly  after  the  appearance  of  the  system  of  Men- 
deleeff  and  the  table  of  Meyer,  Baumhauer  (82 ) sug- 
gested a mode  of  illustrating  graphically  the  relation- 
ship between  the  elements  and,  possibly,  the  derivation, 
or  nature,  of  the  supposed  simple  bodies. 

The  fairly  regular  differences  between  the  groups  were 
given  by  Meyer  in  his  earlier  work.  Baumhauer  gives 
these  differences  as  16,  46,  and  88-92.  He  then  con- 
tinues : 

“ A clear  view  of  the  elements  and,  with  that,  the  ex- 
planation of  many  peculiarities,  is  first  obtained  when 
one  arranges  them  in  accordance  with  increasing  atomic 
weight  in  the  form  of  a spiral,  giving  hydrogen  the  cen- 


1 


position  are 

DLtLym  (95) 
Lajtfhttn  (92) 
Cerium  (92) 
Thorium.  ( 231,5 ) 
Jartjnrt  ium 


Of  doubtful 

Yttrium  ( 61, 7 ) 
Erhuun  ( 112 ,6  ) 
Indium  (37,8) 
Ruthenium  (104,4) 
Rhodium  (104,4) 


baumhauer’s  spiral  arrangement. 


1 2 1 


tral  position.  Similar  elements  fall  under  one  another. 
The  ring-formed  series  in  the  spiral  are  called  central, 
those  reaching  from  center  to  peripheiy  are  radial. 
For  the  sake  of  greater  simplicity  seven  chief  radials  are 
assumed,  some  of  which  are  again  split  up  into  several 
others.  Between  the  radial  and  central  series  numerous 
transitions  show  themselves  which  are  to  be  explained 
by  the  preponderating  influence  of  neighboring  elements. 
Only  when  the  relations  to  all  neighboring  members  of 
the  system  appear  for  each  element  at  the  same  time  and 
with  equal  intensity  will  the  whole  furnish  a perfect 
scheme. 

“ The  relations  to  neighboring  elements  can  be  many 
and  since  they  cannot  be  quantitatively  determined,  it  is 
difficult,  proceeding  from  the  chemical  properties  of  the 
element,  to  assign  it  its  proper  place  in  the  system. 
Generally,  however,  the  position  of  an  element  relative 
to  the  others  can  be  determined  by  a closer  observation 
of  the  clue  given  by  its  characteristics.  The  principle 
followed  can  be  outlined  as  follows  : Each  element  holds 
a position  determined  by  its  chemical  characteristics,  as 
a summary  expression  of  which  the  atomic  weight  may 
be  regarded,  either  upon  the  continuous  series  of  a spiral 
arranged  according  to  increasing  atomic  weight  or  be- 
tween the  rings  of  the  same.  In  the  last  case,  as  well 
as  by  each  interposition  upon  the  spiral  itself,  the  chem- 
ical nature  and  the  atomic  weight  of  the  element  in 
question  is  dependent  upon  the  nature  and  the  atomic 
weight  of  neighboring  elements.  Thus  one  can  calcu- 
late atomic  weights  for  any  blank  positions  upon  the 


122 


THE  PERIODIC  LAW. 


spiral  where  an  element  is  lacking.  This  can  be  only 
imperfectly  done  after  passing  the  atomic  weight  137  as 
so  many  of  the  vertical  and  side  neighboring  elements 
are  lacking. 

“ The  atomic  weight  and  the  chemical  nature  of  an 
element  stand  in  close  connection  with  one  another. 
Still  this  connection  is  not  usually  a simple  one.  On 
the  contrary,  the  atomic  weight  of  an  element  is  com- 
posed of  the  atomic  weights  of  others  in  just  the  measure 
in  which  its  properties  show  themselves  to  be  a complex 
of  other  elements.  This  idea  can  be  brought  under  the 
general  formula 

^ IB  -j-  m C -f-  nD  . . . 

/ + m + n . . 

where  A — the  atomic  weight  of  an  element,  B , C,  D 
atomic  weights  of  related  elements,  /,  m,  71  certain  coef- 
ficients. These  last  express  the  ratio  of  the  magnitude 
of  affinity  of  A with  the  elements  B,  C,  D . . . . Ac- 
cording to  this  formula,  quite  different  elements  can 
have  similar  atomic  weights  whereby  B,  C,  D,  as  well  as 
/,  m,  n , have  a different  meaning  in  each  separate  case. 
Like  elements  also  have  almost  identical  weights  where  B, 
C,  D,  as  well  as  /,  m,  n , change  only  in  slight  degree. 

“ The  form  of  a spiral  was  chosen  for  the  graphic 
representation  of  these  facts  onty  after  man}*  vain  at- 
tempts at  arranging  the  element  in  other  wa5*s  which 
would  express  the  facts  equally  well.  The  typical  ele- 
ments fall  upon  the  spiral  and  their  atomic  weights  form 
an  increasing  series.  They  show  relationship  to  one 
another  and  may  perhaps  in  part  be  referred  to  still  sim- 


ADDITIONAL  WORK  BY  NEWLANDS.  1 23 

pier  types.  The  elements  appearing  as  medial  members 
can  be  recognized  from  their  many-sided  characteristics. 

“ In  this  table  the  relation  of  the  elements  to  one  an- 
other is  indicated  by  arrows  in  the  more  difficult  cases. 

“ The  most  distinguished  chemists  are  united  in  the 
opinion  that  there  exists  one  or  a few  primal  elements 
and  that  our  elements  are  at  most  modifications  or  com- 
binations of  these.  This  idea  is  expressed  in  the  table 
in  the  reduction  of  the  complicated  elements  to  certain 
types,  and  thus  each  series  is  represented  by  its  initial 
member  which  has  the  lowest  atomic  weight.  The 
other  members  differ  from  the  first  in  their  density.  Al- 
most without  exception  the  specific  gravity  increases 
from  the  center  to  the  periphery  of  the  spiral.  We  can 
therefore  assume  that  all  elements  of  any  one  typical 
series  are  only  definite  functions  of  the  first  member. 
Their  atomic  weight  is  gotten  by  the  addition  of  a num- 
ber given  by  the  building  of  the  spiral. 

“ One  can  go  a step  further  and  look  even  upon  these 
initial  members  as  peculiar  and  to  a certain  degree  indi- 
vidualized modifications  of  one  and  the  same  primal 
matter.  This,  however,  is  of  course  only  speculation.” 

The  diagram  follows  and  needs  no  further  explana- 
tion. Its  resemblance  to  that  of  Hinrich’s  will  be  noted. 

9o.  Additional  Work  by  Newlands. — In  1872  New- 
lands  published  his  first  priority  claim  (86).  A little 
later,  in  a short  note,  (87)  he  drew  attention  to  the  oc- 
currence of  the  fourteen  principal  elements,  which  are 
most  widely  distributed  and  which  appear  to  be  essen- 


124 


THE  PERIODIC  LAW. 


tial  to  vegetable  and  animal  life.  He  observed  that  they 
comprise  two  representatives  of  each  of  the  chief  chemi- 
cal groups.  In  this  he  classed  hydrogen  and  chlorine 
together  and  aluminium  and  iron. 

In  1873  he  made  another  priority  claim  before  the 
London  Chemical  Society.  In  1875  he  gave  another 
table  to  be  used  in  text-books  as  a substitute  for  the  old 
alphabetical  lists,  which  have  been  hard  to  displace. 
In  this  he  included  the  ordinal-number,  to  which  he 
continued  to  attach  importance,  the  symbol,  the  atomic 
weight,  and  the  difference  between  each  atomic  weight 
and  the  one  immediately  preceding  it.  He  drew  atten- 
tion to  the  recurrence  of  analogous  elements  at  every 
eighth  interval  and  repeated  his  former  comparison  to 
the  octaves  in  music.  When  the  table  was  given  a hori- 
zontal arrangement,  in  sevens  and  in  sixteen  columns,  he 
remarked  upon  the  quantivalence  of  the  elements  thus 
exhibited. 

In  1878  (104)  Newdands  gave  a table  comparing  the 
atomic  weights  derived  from  four  different  standards  : 
Hydrogen,  1;  Sodium,  10;  Chlorine,  15,  “nearly”; 
and  Carbon,  5.  Comparisons  are  made  with  the  ordi- 
nal numbers.  These  need  not  be  commented  upon  and 
the  following  brief  notes  of  his  will  be  passed  over  with 
bare  mention. 

1.  He  believed  the  atomic  weights  to  be  invariable. 

2.  It  is  possible  that  elements  of  higher  atomic  weight 
might  contain  those  of  lower  atomic  weight,  but  not  the 
reverse. 

3.  If  we  view  all  matter  as  really  composed  of  various 


ADDITIONAL  WORK  BY  NEWLANDS.  1 25 

modifications  of  one  elementary  substance,  consisting  of 
physical  atoms,  we  may  regard  the  atomic  weight  of 
each  element  as  expressing  the  relative  number  of  phys- 
ical atoms  contained  in  the  chemical  atom.  The  same 
number  of  physical  atoms  differently  arranged  might 
form  two  or  more  distinct  elements  which  might  then  be 
regarded  as  isomeric.  Perhaps  cobalt  and  nickel  are 
thus  related. 

4.  With  regard  to  Prout’s  law  ; the  number  of  ele- 
ments whose  atomic  weights  approach,  within  experi- 
mental errors,  to  exact  multiples  of  hydrogen  is  far 
greater  than  it  should  be  on  the  theory  of  probabilities. 

5.  It  sometimes  happens  that  the  atomic  weight  of 
one  element,  when  doubled,  gives  a number  identical, 
or  nearly  so,  with  the  atomic  weight  of  another. 

6.  It  frequently  happens  that  out  of  three  elements 
having  common  properties,  the  atomic  weight  of  one  ap- 
proaches the  mean  of  the  other  two,  as  in  the  well-known 
triplet  groups  or  triads. 

7.  Two  atomic  weights,  taken  from  the  lower  part  of 
the  series,  when  added  together  frequently  equal  the 
atomic  weight  of  some  other  element,  though  no  general 
rule  seems  to  be  applicable  to  such  cases. 

8.  Taking  the  three  lowest  known  atomic  weights, 
those  of  H,  Li,  and  Be  ; many  of  the  higher  atomic 
weights  may  be  arithmetically  derived  from  them  by 
various  combinations. 

9.  Taking  a certain  number  of  elements  whose  weight 
may  be  supposed  to  be  consecutive,  say  the  twenty-eight 
first,  and  arranging  them  in  two  columns,  the  first  half 


126 


THE  PERIODIC  LAW. 


in  order  of  the  atomic  weights  and  the  second  in  reverse 
order,  nearly  a constant  quantity  will  be  gotten  by  add- 
ing together  the  corresponding  members  of  the  two  col- 
umns, if  the  atomic  weights  corresponded  to  the  natural 
order  of  numbers,  or  to  some  multiple  of  such  order. 
As  a matter  of  fact  the  numbers  obtained  vary  consider- 
ably. 

10.  No  simple  relation  could  be  wrorked  out  of  the 
atomic  weights  under  any  other  system  than  that  of 
Cannizzaro,  and  if  we  attempt  to  introduce  various 
equivalents  of  one  element  into  the  table  they  seem  out 
of  place,  as  do  also  the  combining  weights  of  quasi-ele- 
ments, such  as  ammonium  or  cyanogen. 

11.  If  any  data,  as  specific  heats  or  vapor  densities, 
should  prove  ultimately  to  be  without  exception,  either 
directly  or  inversely  as  the  atomic  weights,  a list  of  ele- 
ments arranged  according  to  such  data  would,  of  course, 
also  show  a Periodic  Law. 

12.  Although  all  the  elements  yet  discovered  appear 
to  take  their  places  in  accordance  with  the  Periodic  Law, 
it  is  quite  conceivable  that  various  series  of  elements 
may  exist  not  very  simply  related  to  each  other. 

Newlands’  mind  ran  on  numbers — a mania  for  numer- 
ical relations.  It  was  impossible  for  him  ever  to  have 
developed  the  Periodic  Law. 

91.  The  Synoptical  Table  of  Qibbes. — A “Synoptical 
Table  of  the  Elements”  was  published  byL.  R.  Gibbesin 
1875,  in  the  proceedings  of  the  Elliott  Society  of  Charles- 
ton (95).  It  purported  to  be  a table  prepared,  two  or 
three  years  before,  for  the  illustration  of  his  lectures  to 


THE  SYNOPTICAL  TABLE  OF  GIBBES 


1 2 7 


Groups. 


128 


THE  PERIODIC  LAW. 


his  class.  It  is  mentioned  thus  in  detail  because  the 
main  interest  attaching  to  it  is  that  a professor  in  a re- 
mote and  small  American  college  should,  a few  years 
after  the  appearance  of  Mendeleeff’s  paper,  have  worked 
out  for  himself,  evidently  in  ignorance  of  the  work  of 
Meyer  and  Mendeleeff,  some  of  the  most  important  prin- 
ciples of  the  Periodic  Paw.  The  evidence  of  this  ignor- 
ance is  presumptive ; first,  because  his  table  was  very 
crude  and  certainly  would  scarcely  have  been  offered  to 
his  classes  had  the  author  known  of  the  much  superior 
ones  which  had  just  appeared  ; secondly,  he  carefully 
mentioned  all  authorities  known  to  him  and  upon  whom 
he  had  drawn  in  the  construction  of  his  table.  He  fore- 
stalled two  or  three  later  authors  in  his  methods  of  graphic 
representation  of  the  law. 

The  relations  the  author  desired  to  exhibit  in  his 
synoptical  table  were  : to  show  the  groups  of  elements 
as  at  present  recognized,  the  atomic  weights  of  each  ele- 
ment as  now  adopted,  the  character  of  each,  as  artiad 
or  perissad,  the  valence,  and  the  electro-chemical  char- 
acter. In  the  discussion  of  his  table,  he  remarked  : 

“ Now  reading  each  series  downwards,  beginning 
with  A,  and  following  the  order  of  the  letters  (see  table) 
a remarkable  regularity  will  be  observed  in  the  succes- 
sion of  the  numbers,  as  far  as  the  arrangement  has  been 
now  described,  yet  with  gaps  unfilled  by  numbers  in 
several  of  the  groups.” 

Influenced  and  guided  by  this  order  of  succession  he 
made  several  changes  in  the  groups  as  given  by  Barker, 
(whose  Text-Book  of  Chemistry  he  was  following.) 


THE  SYNOPTICAL  TABLE  OF  GIBBES. 


129 


The  author  observed  that  in  this  table  the  continuity  or 
regularity  in  the  series  of  numbersis  very  striking ; the 
perissad  or  artiad  character  of  each  series  is  preserved 
throughout ; also,  with  a few  exceptions  the  prominent 
degree  of  equivalence  is  well  preserved  and  indicated ; 
the  electro -chemical  character,  in  addition,  is  very  fairly 
presented. 

Anyone  series,  he  said,  maybe  expressed  by  an  equa- 
tion P — Qa  where  a is  the  number  with  its  sign,  which 
expresses  the  atomicity.  In  series  A it  is  approximately 
5 + 2(2,  in  series  B,  20  + 2 a,  in  series  C,  30+  2a,  etc. 
The  numbers  in  the  first  three  series  A,  B,  C may  be  re- 
presented very  closely  by  an  arithmetical  series  whose 
first  term  is  7 and  equi-difference  2.  The  average  differ- 
ence for  numbers  on  the  same  line  in  series  B and  C and 
also  in  A and  B is  16;  for  C and  E , the  difference  is 
about  46  and  between  E and  G about  48  (3  X 16.)  The 
occurrence  of  Dumas’  triads  and  his  parallelism  in  the 
table  are  pointed  out.  The  recurrence  of  multiples  of  eight 
in  the  groups  and  in  the  differences  between  the  series 
is  also  remarked  upon,  showing  the  influence  of  the  ear- 
lier workers  upon  the  author. 

In  his  diagram  he  gave  upon  the  horizontal  axis,  right 
and  left  from  the  center,  the  positive  and  negative  elec- 
tricities as  abscissae.  The  atomic  weights  are  laid  off  as 
ordinates  upon  the  vertical  axis  rising  from  a zero  atom- 
icity. This  gives  the  elements  in  an  ascending  scale  of 
atomic  weights  though  they  are  broken  up  into  series. 
With  very  acute  reasoning  and  insight  Gibbes  showed 
that  the  three  series  may  be  exhibited  in  continuity  as 


130  THE  PERIODIC  LAW. 

one,  that  is  by  the  use  of  an  Archimedean  spiral  whose 
radius  vector  increases  by  16  units  in  one  revolution. 

GIBBES’  DIAGRAM. 


This  is  the  helix  of  Tothar  Meyer,  and  of  De  Chancourtois, 
and  the  spiral  of  Mendeleeff.  His  diagram  will  on  ex- 


THE  SYNOPTICAE  TABEE  OF  GIBBES.  131 

amination  be  seen  to  be  based  on  the  same  principles  as 
those  of  Spring,  Reynolds,  and  Crookes. 

The  author  went  further  and  anticipated  some  of  the 
work  of  Haughton.  He  observed  that  no  linear  equation 
could  be  constructed  to  give  more  than  rude  approxima- 
tions to  the  atomic  weights,  and  that  to  construct  curves, 
two  points  of  inflection  of  contrary  curvature  must  be 
given.  These  are  the  serpentine  cubics  afterwards  given 
by  Haughton.  He  cautioned  against  laying  too  much 
stress  upon  such  arithmetric  and  geometric  exercises. 

It  seems  remarkable  that,  with  so  imperfect  a table,  so 
much  of  the  later  work  done  with  the  perfected  tables, 
given  by  the  authors  of  the  Periodic  Law,  should  have 
been  anticipated,  especially  when  we  notice  how  slight 
was  Gibbes’  idea  of  periodicity.  He  gave  in  his  table 
seven  groups,  it  is  true,  four  negative  and  three  positive, 
but  they  are  very  poorly  filled  outandhe  showed  no  com- 
pleted period  of  seven  in  the  entire  table.  His  “regular- 
ity” can  scarcely  refer  to  periodicity. 

He  found  something  of  what  Meyer  calls  Double  Peri- 
odicity. Under  each  of  the  groups  of  his  table  he  noted 
th  at  two  sub-groups  might  be  distinguished.  These  are 
not  clearly  shown  on  every  line  but  taking  line  2 the 
series  B,  D,  F,  gives  one  secondary  sub-group  ; C,  E,  G, 
gives  the  primary  sub-group.  In  a note  he  said  that  Hg 
could  only  find  a place  in  series  H,  I line  2.  He  had  not 
so  inserted  it  because  of  the  novelty  of  its  finding  a place 
in  the  calcium  group.  If  this  be  done  and  it  be  called 
a member  of  the  magnesium  sub-group,  then  the  differ- 
ence between  its  atomic  weight  and  that  of  cadmium, 


132 


THE  PERIODIC  LAW. 


namely  88,  will  be  exactly  the  same  as  between  those  of 
Mo  and  W and  between  those  of  Cb  and  Ta.  But  then 
the  continuity  of  sequence  would  have  been  broken  by 
an  inversion,  the  number  200  exceeding  some  of  those 
that  followed  it. 

92.  The  Concentric  Ring  Arrangement  of  Wiik. — 

In  the  same  year  that  this  article  of  Gibbes  was  pub- 
lished, Wiik  (96)  made  an  attempt  at  grouping  the  ele- 
ments. He  first  gave  a critical  notice  of  the  arrange- 
ments of  Mendeleeff,  Meyer,  and  Baumhauer.  I11  his 
own  work  he  laid  especial  stress  upon  the  electro-chem- 
ical theory  of  Berzelius.  Much  of  it  is  based  upon  min- 
eralogical  data  and  conceptions. 

In  his  arrangement  of  the  elements  he  made  use  of 
three  concentric  circles  which  contained  the  three  series : 

1.  Non-Metallic  or  Primary  Elements. 

2.  Half-Metallic  (including  metalloids)  or  Secondary 
Elements. 

3.  Characteristically  Metallic  (heavy)  or  Tertiary 
Elements. 

These  circles  were  divided  by  three  radii  into  positive, 
negative  and  indifferent  elements  with  H,  O,  and  N, 
respectively,  as  initial  elements  for  each  electro-chemical 
group.  He  suggested  that  the  oxides  Be203,  ThO,  etc., 
would  be  in  better  accord  with  his  arrangement  than  the 
ones  known;  also  certain  changes  in  the  atomic  weights. 
In  another  table  he  brought  out  the  fact  that  the  differ- 
ences between  the  atomic  weights  were  frequently  multi- 
ples of  16,  14  or  1 by  3 or  6 and  also  that  many  of  them 
were  multiples  of  12  or  of  4.  These  differences  he  thought 


WIIKS’  TABES. 


133 


134 


THE  PERIODIC  RAW. 


closely  related  to  the  ozone  and  antozone  of  Schonbein. 
From  this  he  was  led  to  consider  the  primal  elements. 
In  oxygen,  which  is  indifferent,  he  found  the  presence  of 
+ 0 = 4and  — 0=  12,  the  same  numbers  noted  above. 
He  found  a further  relationship  between  the  sums  of  the 
atomic  weights  of  the  indifferent  and  electro-positive 
and  electro-negative  elements  and  their  differences.  The 
specific  gravities  and  melting  points  were  also  considered 
in  another  table. 

His  theory  as  to  the  genesis  of  the  elements  was  built 
uponLaplace’sTheoryofthe  Heavens, Berzelius’  Electro- 
Chemical  Theory  and  Edlung’s  Theory  of  Electricity.  The 
ether  is  supposed  to  be  at  a different  electric  potential  at 
different  points  and  if  it  should  then  segregate,  it  would 
take  on  a different  character  at  one  point  from  that  at 
another.  For  example,  it  might  be  in  excess  at  one 
point  and  deficient  at  another.  Suppose  these  were  in 
the  ratio  of  3 to  1,  then — O and-(-0  would  be  formed 
where  the  ratios  are  12  to  4,  etc.  The  ether  thus  goes 
over  into  matter  and,  when  of  the  proper  mass,  would 
yield  all  the  elements. 

A last  table  is  given  in  which  the  elements  are  ar- 
ranged in  the  form  of  a V,  thus : 

V=5i.3H=i 


Each  half  contains  31  elements  and  they  are  united  by 
Li.  One  half  has  the  heavy,  the  other  the  light  and  non- 
metals. 


waechter’s  numerical  regularities.  135 

The  occurrence  of  the  elements  in  the  outer  layers  of 
the  earth’s  crust  was  considered  and  lastly  the  applica- 
bility of  the  theory  to  the  entire  inorganic  world. 

93.  The  Primal  Element  of  Simmen. — Simmen  (97) 
formed  an  hypothesis  of  a primal  element  and  assumed 
that  the  atoms  of  the  supposed  simple  bodies  were  built 
up  of  the  atoms  of  this  primal  element.  As  each  primal 
atom  had  the  same  weight,  the  difference  in  the  atomic 
weights  of  the  elements  was  due  to  the  different  number 
of  primal  atoms  brought  together  in  each.  Besides  the 
number,  the  form,  size,  etc.,  of  the  primal  atoms  exercise 
their  influence  upon  the  properties  of  the  elements ; thus 
he  thought  the  valence  dependent  upon  the  form  of  the 
atom.  Chemical  force  was  looked  upon  as  identical  with 
the  force  of  attraction.  This  diminished  with  the  square 
of  the  distance  but  never  entirely  disappeared. 

94.  Waechter’s  Numerical  Regularities. — In  1878 
there  was  a paper  by  Waechter  (106)  in  which  the  old 
question  of  the  numerical  regularities  was  again  taken 
up.  The  regularities  recorded  were  : 

1.  A table  beginning  with  the  first  period  of  Mende- 
leeff  and  giving  the  elements  in  the  different  groups 
whose  atomic  weights  differ  from  those  of  the  first  seven 
by  16  or  a multiple  of  16.  Thus  the  horizontal  lines  in 
the  table  contain  elements  of  the  same  valence  whose 
atomic  weights  increase  by  a multiple  of  16  approxi- 
mately. 

2.  The  following  can  be  shown  true  of  these  elements. 
The  arithmetic  mean  of  the  atomic  weights  of  two  ele- 


The  Table  of  Waechter. 


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137 


ments  with  equally  intense  but  opposite  affinity  are 
nearly  equal  to  one  another.  That  is,  they  equal  76. 
This,  the  author  said,  corresponded  to  a hypothetical  ele- 
ment forming  the  middle  of  the  series. 

F-fCs  Q O+Ba  N+Di  , 

= 75-998:—^ =76.583:  =76.272: 

I+Na  Te  + Mg  , Sb  + A1 

— - — =74-99: — -=76.19:  = 75-372- 

Further  laws  as  to  the  affinities  of  these  elements,  the 
melting  points  and  boiling  points,  the  specific  heats, 
J:he  specific  gravities  etc.,  are  given.  His  table  is  given 
on  page  136. 

95.  Lockyer’s  Hypothesis  as  to  the  Compound  Na= 

ture  of  the  Elements. — A paper  (107)  read,  in  the  year 
1878  before  the  Royal  Society,  by  Lockyer  upon  a 
working  hypothesis  that  the  elements  are  in  reality  com- 
pound bodies  created  a great  deal  of  comment  and  dis- 
cussion. This  paper  may  be  summed  up  as  follows  : 

While  engaged  upon  the  task  of  mapping  the  spec- 
trum of  the  sun  with  the  Frauenhofer  lines  and  compar- 
ing them  with  the  spectra  of  known  elements,  the  author 
met  with  many  facts  which  led  him  to  propound  the  hy- 
pothesis that  the  elements  were  after  all  compound  bodies 
and  not  simple.  The  spectroscopic  evidence  led  him 
to  believe  that  there  was  a decomposition  of  the  elements 
brought  about  by  the  intense  heat  of  the  sun  and  other 
bodies. 

The  hotter  a star,  the  more  simple  its  spectrum  seems 
to  be.  Thus  Sirius,  which  is  at  least  one  of  the  bright- 
est of  stars,  furnishes  a spectrum  showing  only  very 
thick  hydrogen  lines  and  a few  very  thin  metallic  ones, 


138 


THE  PERIODIC  RAW. 


characteristic  of  elements  of  low  atomic  weight.  And 
this  is  true  of  other  very  bright  ones.  The  cooler  ones, 
as  our  sun,  contain  a much  larger  number  of  metallic 
elements  but  no  non-metals,  and  the  coolest  furnish  band 
spectra,  characteristic  of  compounds  of  metallic  with 
non-metallic  elements.  These  facts  appear  to  meet  with 
a simple  explanation  if  it  be  supposed  that,  as  the  tem- 
perature increases,  the  compounds  are  first  broken  up  in- 
to their  constituent  elements  and  that  these  elements 
then  undergo  dissociation  into  elements  of  lower  atomic 
weight. 

With  regard  to  the  hydrogen  spectrum,  Lockyer  stated 
that  he  had  obtained  evidence  leading  to  the  conclusion 
that  the  substance  giving  the  non-reversed  line  in  the 
chromosphere,  which  had  been  termed  helium,  and  not 
previously  indentified  with  any  known  form  of  matter, 
and  also  the  substance  giving  the  1.474  or  coronal  line, 
are  really  other  forms  of  hydrogen,  the  one  more  simple 
than  that  which  gives  the  H- line  alone  and  the  other 
more  complex  than  that  which  gives  the  A-line  alone. 

96.  Berthelot’s  Discussion  of  Lockyer’s  Hypothesis. 
— Shortly  after  the  publication  of  Lockyer’s  Hypothesis 
there  appeared  (108)  the  following  criticism  from  Berthe- 
lot : “I  think  the  hypothesis  of  a progressive  decom- 

position of  all  substances  through  increasing  tempera- 
ture, bringing  first  compound  substances  to  the  elements 
known  to  chemists,  and  then  again  to  yet  simpler  ele- 
ments, is  to  be  enunciated  with  reserve. 

“Simple  substances,  as  we  know  them,  bear  certain 
positive  characters  not  belonging  to  compounds,  e.g.,  the 


zaengerle’s  numerical  relations.  139 

relation  between  specific  heat  of  a substance,  the  gaseous 
density  and  atomic  weight  relation,  independent  of  tem- 
perature. 

“There  is  between  the  physical  properties  of  the  ele- 
ments and  those  of  their  compounds,  a singular  opposi- 
tion. This  opposition  does  not  at  all  prove  the  theoret- 
ical impossibility  of  decomposing  our  actual  elements, 
but  it  better  defines  the  conditions  of  the  problem,  and 
leads  us  to  think  that  the  decomposition  of  our  simple 
substances,  if  it  may  occur,  must  be  accompanied  by 
phenomena  of  quite  a different  order  from  those  which 
have  hitherto  determined  the  destruction  of  our  compound 
substances.’’ 

97.  Crookes’  Views  as  to  the  Same. — At  the  same  time 

(109)  there  was  the  following  expression  of  opinion  from 
Crookes:  “ Even  at  present,  therefore,  until  some  part 

is  shown  to  be  irreconcilable  with  Mr.  Lockyer’s  views 
we  consider  ourselves  perfectly  justified  in  giving  them 
our  provisional  adhesion,  as  a working  hypothesis  to  be 
constantly  tested  by  reference  to  observed  phenomena.’’ 

Crookes  went  further  and  heralded  Eockyer  as  the 
“ Darwin  of  the  inorganic  world.” 

98.  Zaengerle’s  Numerical  Relations. — In  1871,  Zan- 
gerle  (88),  to  whose  work  we  shall  have  to  refer  again, 
had  come  to  the  conclusion  that  “all  of  the  atomic 
weights  are  the  sum  of  two  or  three  products,  the  first 
of  which  is  gotten  by  the  multiplication  of  one  of  the  six 
fundamental  numbers  by  a whole  number,  whilst  the 
second,  or  the  two  others,  are  gotten  by  the  multiplication 
of  one  or  two  of  the  six  difference  numbers  by  also  whole 


140 


THE  PERIODIC  EAW. 


numbers.”  He  found  it  necessary  in  the  use  of  these 
numbers  to  allow  himself  very  wide  latitude. 

99.  Lersch’s  Numerical  Relations. — Lersch  (112),  in 
criticising  the  work  of  Zangerle,  remarked:  11  By  the 
combination  of  such  elastic  products  it  is  naturally  ex- 
tremely easy  to  obtain  any  desired  atomic  weights,  es- 
pecially if  one  neglects  the  decimals.”  Lersch  endeav- 
ored to  find  out  for  several  of  the  groups  some  one  ‘ ‘ fun- 
damental value”  or  number  of  which  they  are  all  exact 
multiples.  For  instance  A1  = 13  X 2.1  ; La  = 44X2.1: 
Cr=  25X2.1;  Th  = 55X2.1;  Ce  = 66X2.1.  Pursu- 
ing this  idea  further  he  made  use  of  one-half  of  the 
square  root  of  one  of  the  atomic  weights  in  a group  as  the 
fundamental  value ; thus,  the  square  root  of  the  atomic 
weight  of  Cu  is  7.9379;  this  divided  by  two  is  the  funda- 
mental value,  or  g;  2jg  = Ag;  28g  = Cd  ; 52^=  Pb. 
In  other  groups  a difference  number,  d,  is  made  use  of. 
Thus : 


Lithium  group 

g = 7- 

Magnesium  group  g = 8. 

Li  7 

Mg  8 

Na  7+16 

= 23 

Mg  8+15.95  = 23.95 

K 7+2X16 

= 39 

Ca  8+15.95  = 39.9 

Rb  3X7+4X  16 

= 85 

Sr  3X8+4X15.8  = 87.2 

Cs  3X7+7X16 

= 133 

Ba3X8+7X  16.11  =136.8 

Various  groups  can  be  built  up  by  the  use  of  the  fun 

damental  and  the  difference  numbers.  Thus  : 

Lithium  group  has  g = 4 

and  d = 1.174  ( = -* /19  ) 

Magnesium  “ 

“ g = 4 

“ d=  1. 174  ^ v / 

Nitrogen  “ 

“ g=  5 

“ d = 1. 174 

Oxygen  “ 

“ g=  8 

“ d = 1. 174 

Beryll  “ 

“ g = 9 

“ d = 1. 174  f 4 | v 

Fluorine  “ 

“ g = 7 

“ d=  2.486  (almost  38  1 

lersch’s  numerical  relations.  141 

The  various  atomic  weights  may  then  be  worked  out 
as  follows:  4 g + 6 d for  Na;  33  g + 4 d for  Ba; 
4^  + x7  d for  Fe,  etc. 

Lersch  then  discussed  the  relation  of  the  square  root 
of  the  first  member  to  the  other  members  of  the  group. 
He  found  that  when  one-half  this  square  root  is  multiplied 
by  16  the  second  member  of  the  group  is  obtained.  For 
the  others  he  failed  to  show  any  note- worthy  regularity. 
To  improve  the  results  he  made  use  of  some  quite  com- 
plex formulas.  He  next  examined  the  relations  existing 
between  the  square  roots  of  the  atomic  weights  of  the 
different  members  of  a group.  These  are  not  simple. 
The  cubic  roots,  he  said,  yield  no  satisfactory  relations. 

His  next  effort  was  to  discover  some  relation  by  taking 
the  four  members  of  a group  as  equal  to  1000  and  then 
apportioning  this  among  them  according  to  the  ratio  of 
their  atomic  weights.  These  numbers  are  then  com- 
pared in  various  ways.  The  squares  of  the  atomic 
weights  are  then  examined.  Thus  he  finds  (i22  + 
28s)  2j  — 48s  nearly.  That  is  for  the  carbon  group.  For 

K,  Rb,  and  Cs  he  gets  132.5,  etc.  At 

the  close  of  his  paper  upon  the  numerical  relations  to  be 
observed  in  the  system  of  planets,  he  remarked  that  the 
ratio  of  the  atomic  weights  of  fluorine  and  chlorine  to 
one  another  approached  very  closely  to  that  of  the  dis- 
tances of  the  sun  from  Mercury  and  Venus.  And  so  the 
ratio  between  fluorine  and  bromine  approached  that  of 
the  distances  from  Mercury  and  Mars.  Other  chemico- 


142 


THE  PERIODIC  LAW. 


astronomical  ratios  are  given,  allot  which  seem  decidedly 
“bizarre”  to  use  the  language  of  one  of  his  critics. 

100.  Zaengerle’s  Primal  Elements. — In  1882,  Zangerle 
( 1 2 1 ) attempted  to  account  for  the  regularities  in  the  prop- 
erties of  the  elements  upon  the  ground  of  several  primal 
elements  and  then  later  upon  the  assumption  of  one. 
He  divided  the  elements  into  various  groups  and  distin- 
guished three  series  in  each  group  : one  electro-negative, 
one  intermediate  and  one  electropositive.  In  the  inter- 
mediate stood  the  fundamental  or  type-element,  in  the 
two  others  the  atomic  weight  increased  from  element  to 
element  by  a definite  increase.  These  two  increments 
and  half  the  atomic  weight  of  the  type  represent  the 
atomic  weights  of  the  three  primal  elements  forming  the 
bases  of  each  group.  Take,  for  example,  the  carbon 
group : The  atomic  weights  forming  the  basis  are 

A = ^ = 6;  = 21  ; and/ = 22.  Then  one  gets  the  in- 

termediate series  C—A a ; Sn  =At-\-Et-\-J ; Th  = A3-\-Ee 
+ Jt.  Electro-negative  group,  Si  = A — |—  ; Ti  = A -j-/,; 
Nb  = A + /4 ; Ta  — A-\-J&.  Electro-positive  series 
Zr  = A -f-  E 4 . 

Thus  one  sees  that  only  in  the  intermediate  series  do 
all  three  primal  elements  make  their  appearance.  Since 
/ is  negative  and  E is  positive,  the  differences  in  the 
electro-chemical  behavior  can  be  ascribed  to  the  rela- 
tions of  A,  E and  J to  one  another. 

Leaving  these  three  primal  elements,  Zangerle  went, 
beyond  the  reach  of  all  experiment,  to  a single  original 
element  out  of  which  all  the  others  are  supposed  to  be 
formed.  This  is  the  hypothetical  ether  of  space  and  to 


zaengerle’s  primal  elements.  143 

it  he  assigned  the  atomic  weight  0.0001 . The  differences 
between  the  atoms,  as  we  know  them,  depend  either  upon 
their  formation  out  of  unequal  amounts  of  this  ether,  or 
upon  a different  arrangement  of  the  atoms,  or  finally  upon 
differences  in  the  directions  and  number  of  the  vibrations 
of  the  primal  atoms.  These  primal  atoms  form  condensa- 
tions of  three  grades.  The  condensations  of  the  first 
grade  are  the  molecules  of  the  primal  matter.  Out  of 
these  molecules  condensations  of  the  second  grade  are 
formed,  namely  the  atoms  of  the  various  elements.  His 
further  conception  is  something  like  the  composite  ele- 
ments of  Brodie  (p.  70).  He  spoke  of  some  of  the  ele- 
mentary atoms  as  being  formed  out  of  the  primal  mole- 
cules combined  with  «-,  /?-,  or  y-oxygen,  which  oxygen 
is  to  determine  the  periodicity.  Condensations  of  the 
third  grade  are  finally  the  molecules  of  the  elements  and 
the  compounds.  The  system  of  symbols  used  is  some- 
what like  that  of  Brodie. 

Now  upon  these  hypotheses  just  mentioned,  Zangerle 
built  up  a natural  system  of  the  elements  and  gave  a 
very  full  table,  which  is  here  copied  in  part.  All  the 
elements  are  divided  into  hydrogenoids  and  oxygenoids 
and  these  two  main  groups  fall  again  into  the  six  natu- 
ral families  ; that  of  hydrogen,  of  beryllium,  of  boron,  of 
carbon,  of  nitrogen  and  of  oxygen.  Each  family  has 
several  groups, at  the  head  of  each  of  which  a typical  ele- 
ment stands.  Thus  in  the  hydrogen  family  there  are 
the  types  H,  Na,  and  Mg  with  their  groups.  These  are 
again  separated  into  series  and  those  with  odd  atomicity 
fall  in  one  series  and  those  with  even  in  another.  The 


144 


THE  PERIODIC  LAW. 


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zaengerle’s  primal  elements.  145 

different  atomicity  arises  from  the  combination  of  a typ- 
ical element  with  one  of  the  primal  molecules.  Oa  15.96, 
or  Ob  16.96,  or  Oc  17.96.  The  series  differ  in  their  electro- 
chemical character.  Elements  of  uneven  atomicity  are 
electro-negative  those  of  even  atomicity  are  electro-posi- 
tive and  further  the  hydrogenoids  are  positive  towards 
the  oxygenoids. 

Zangerle  maintained  (88)  that  the  properties  of 
the  elements  are  in  gradations  and  that  these  gradations 
correspond  to  the  atomic  weights.  Ten  such  gradations 
are  observed.  The  atomic  weights  of  the  negative  and 
positive  elements  yield  the  same  differences  from  grada- 
tion to  gradation  with  few  exceptions.  ■ These  differen- 
ces range  between  16  and  24  and  may  be  calculated  by 
the  formula  ( B — f ) : d where  B—  atomic  weight  of  any 
chemical  element  a = atomic  weight  of  the  primal  ele- 
ment and  d = gradation. 

The  atomic  weight  of  any  element  may  be  calculated 
by  means  of  the  formula  f -f -dx  where  a~  atomic 
weight  of  the  primal  element,  d — gradation  and  x = 
differential  of  the  series. 

A portion  only  of  Zangerle’s  table  can  be  given  as  a 
specimen  of  his  method  of  grouping  ; namely,  out  of  the 
hydrogen  family  the  Na  and  Mg  groups,  and  from  the 
oxygenoids  the  nitrogen  group.  It  will  be  seen  that 
here,  there  is  no  talk  of  one  single  series  of  elements  w7ith 
increasing  atomic  weight.  The  atomic  weights  increase 
only  in  the  series,  as  a rule  in  the  horizontal  succession. 
The  chemical  and  physical  properties  of  the  elements 
stand  in  a simple  relation  to  one  another  ; they  change 


146 


THE  PERIODIC  LAW. 


in  periods  with  the  atomic  weights.  The  elements  of 
any  series  are  for  the  most  part  homologous  compounds 
of  the  primal  element  with  oxygen,  hence  their  character 
changes  with  the  contents  of  oxygen.  At  the  same 
time  it  must  be  considered  whether  the  oxygen  atoms 
are  in  even  or  uneven  numbers  combined  with  the  pri- 
mal element.  For  instance  : Li;  LiOa  = Na  ; LiOb  = 
Mg;  the  character  of  Li  not  yet  much  altered.  LiOas= 
K;  LiOaOb=Ca;  slight  change  to  be  noted.  Li20a2 
Cu;  Li20b3=Zn;  complete  change  of  character. 

Zangerle  further  gave  these  rules  : 

“In  the  case  of  the  hydrogenoids  the  basic  character 
increases  with  increasing  atomic  weight  in  the  electro- 
positive series, the  acid  in  the  electro-negative,  whilst  by 
the  oxygenoids  the  opposite  is  true.  In  any  series  the 
atomic  volume  of  the  elements  increases  in  simple  ratio 
with  the  atomic  weights.  The  melting  points  and  the 
boiling  points  show  themselves  joined  to  the  atomic 
weights  in  the  same  way  but  in  different  methods  in  the 
different  series.” 

Zangerle  claimed  for  his  system  the  possibility  of  pre- 
dicting unknown  properties  of  known  and  unknown  ele- 
ments, the  prediction  of  these  elements  themselves,  the 
correction  of  their  atomic  weights  and  other  constants. 
He  gave  a second  table  in  which  he  endeavored  to  make 
clear  the  connections  between  the  properties  of  the  ele- 
ments and  their  atomic  weights. 

Gretschel  and  Bornemann  (135)  seem  to  regard 
the  work  of  Zangerle  as  giving  “more  or  less  clear 
echoes  of  the  hypothesis  of  Prout,  the  ideas  of  Brodie 


CRITICISM  OF  MEYER  AND  SEUBERT.  147 

and  the  periodic  system  of  Mendeleeff . The  regularities 
and  relations  of  the  latter  are  repeated  and  it  is  in  a 
measure  an  elaboration  of  it.” 

Zangerle  concluded  his  work  with  the  hope  of  soon 
bringing  experimental  proofs  of  his  theories. 

101.  The  Criticism  of  rieyer  and  Seubert. — After 
speaking  of  Zangerle  and  his  hypothesis  (147)  Meyer 
and  Seubert  say : ‘ * Speculations  of  this  kind  are 
far  removed  from  any  possibility  of  experimental  proof, 
and  can  therefore  never  be  expected  to  receive  from  it 
any  support.  Nor  can  we  ever  hope  to  receive  any  es- 
sential extension  of  our  knowledge  in  respect  to  primal 
matter  through  a more  accurate  establishment  of  the 
atomic  weights  ; the  next  important  progress  will  rather 
be  brought  about  by  the  decomposition  of  the  elements 
into  a similar  substance,  differing  from  them  however, 
which  may  be  the  primitive  matter  itself,  or  a condensa- 
tion product  of  it.  The  solution  of  this  question,  that 
is,  the  decomposition  of  all  the  elements  into  one  and 
the  same  original  substance,  we  can  hardly  ever  expect 
to  accomplish. 

‘‘The  universal  ether,  with  an  atomic  weight  of  0.0001 
(H  = 1),  has  been  assumed  as  the  primitive  substance 
of  which  all  other  elements  were  formed.  The  atomic 
weights  of  all  other  elements  must  of  course  be  whole 
multiples  of  this,  since  none  of  them  have  been  accurately 
determined  to  the  fourth  decimal  place,  while  many  are 
certain  only  to  the  first  or  second  place,  and  some  only  to 
units  of  hydrogen.” 


148 


THE  PERIODIC  DAW. 


102.  Meyer’s  Ideas  as  to  the  Elements. — In  his  origi- 
nal paper  (81)  announcing  his  System,  Meyer  spoke 
of  the  elements  as  follows  : 

“ That  the  until  now  undecomposed  chemical  elements 
are  'absolutely  undecomposable  is,  at  present  at  least, 
very  improbable.  Rather  it  seems  that  the  atoms  of  the 
weights  are  not  the  ultimate  but  the  proximate  constit- 
uents of  the  molecules,  as  well,  of  the  elements  as  of 
their  compounds.  The  molecules  are  to  be  regarded  as 
particles  of  a first  order,  the  atoms  as  such  of  a second  or- 
der which  again  consist  of  particles  of  a third  higher  or- 
der. 

“The  nature  of  these  components  of  the  atoms  was 
sought  for  shortly  after  the  general  acceptance  of  Dalton’s 
atomic  theory,  see  Prout’s  hypothesis.’’ 

103.  Groshans  on  the  Nature  of  the  Elements. — Alone 
series  of  articles  was  contributed  by  Groshans  (94)  upon 
this  subject.  They  dealt  mainly  with  the  formulas  and 
physical  properties  of  the  compounds  of  carbon.  From  the 
consideration  of  these,  he  arrived  at  the  conclusion  that 
carbon,  hydrogen  and  oxygen  are  simple  bodies  or  true 
elements  ; that  chlorine  is  a compound  body,  consist- 
ing of  four  atoms  of  simple  unknown  bodies ; so  too  bro- 
mine is  a compound  body  consisting  of  nine  atoms. 

His  work  is  criticized  and  the  conclusions  refuted  by 
Mendeleeff  (99). 

104.  Other  Authors  during  this  Period. — Itisunneces- 
sary  to  quote  from  the  work  of  Knowles  (92)  and  of 
Ludwig  as  they  have  little  bearing  here. 


OTHER  AUTHORS  DURING  THIS  PERIOD. 


149 


Blomstrand’s  (78,  79)  effort  to  rehabilitate  the  dualis- 
tic  and  electro-chemical  theories  of  Berzelius  was  a very 
earnest  and  faithful  one  but  met  with  no  success.  His 
division  of  the  elements  into  the  hydrogen-group  and  the 
oxygen-group  may  be  mentioned. 


CHAPTER  VI. 

THE  DEVELOPMENT  OF  THE  NATURAL  LAW. 

1880-1885. 

As  soon  as  the  Periodic  Law  had  come  to  be  recog- 
nized as  a discovery  of  importance,  the  question  as  to  who 
should  rightly  be  considered  its  discoverer  became  also 
a matter  of  moment.  The  claims  of  both  Mendeleeff 
and  Meyer  were  urged  by  themselves  and  their  friends. 
This  discussion  will  not  be  entered  into  here.  The 
Royal  Society  of  England  gracefully  and  justly  solved 
the  question  by  awarding  in  1882  the  Davy  medals  to 
both  Mendeleeff  and  Meyer  as  the  independent  discov- 
erers of  the  Law. 

The  Royal  Society  met  with  some  criticism  because, 
by  this  action,  it  overlooked  and  ignored  the  claims  of 
Newlands.  It  must  be  said  that,  though  unquestionably 
a forerunner  in  the  discovery,  little  was  known  of  his 
claims  at  that  time.  Victor  Meyer  (142)  in  a sum- 
mary of  Prout’s  hypothesis  and  the  periodic  system 
makes  no  mention  of  Newlands. 

io5.  Revival  of  Prout’s  Hypothesis. — Attention  was 
again  drawn  to  Prout’s  Hypothesis  in  its  original  form 
by  Mallet’s(  1 14)  masterly  revision  of  the  atomic  weight  of 
aluminium  and  his  appended  remarks,  and  by  Dumas’ 
discovery  (105  ) of  an  error  in  the  work  of  Stas.  This  was 
his  overlooking  the  absorption  of  oxygen  by  melted  silver. 

Stas’  work  centered  around  the  determination  of  the 
silver-h}Tdrogen  ratio  and  this  implied  a correction  in 
many  of  his  results  which,  at  least,  opened  up  the  ques- 


152 


THE  PERIODIC  LAW. 


tion  once  more  as  to  whether  they  were  integral  multi- 
ples. 

106.  rieyer  aud  Seubert’s  Review  of  Dumas’  Work. 

— These  authors  (146)  after  careful  critical  examination 
of  Dumas’  and  Stas’  work  came  to  the  following  con- 
clusions : 

“The  atomic  weight  of  silver,  as  well  as  the  atomic 
weights  of  numerous  other  elements,  all  contradict  Prout’s 
hypothesis  in  its  characteristic  original  conception.  It 
must,  therefore,  be  looked  upon  as  having  been  disproved 
by  experiment.  In  its  new  forms  it  has  likewise  been 
disproved,  so  far  as  this  is  possible  in  the  present  state 
of  our  knowledge.  Beyond  this  it  amounts  merely  to 
philosophical  speculation  concerning  an  idea  whose  prop- 
able  correctness  will  be  denied  by  no  one — the  Unity  of 
Matter.’’ 

107.  Hallet’s  Views  Regarding  the  Hypothesis  of 

Prout. — At  the  conclusion  of  his  work  (114)  upon  the 
atomic  weight  of  aluminium  this  author  observed  : 

“It  is  interesting  to  observe  that  this  result  also  adds 
one  to  the  cases  already  on  record  of  the  numbers  rep- 
resenting carefully  determined  atomic  weights  approach- 
ing closely  to  integers,  and  leads  to  a word  on  the  re- 
consideration of  “ Prout’s  Law.’’  The  recent  researches 
of  Mr.  Uockyer,  not  unsupported  by  evidence  drawn 
from  other  sources,  have  tended  to  suggest  the  possi- 
bility, at  least,  that  the  forms  of  matter  which,  as  known 
to  us  under  ordinary  conditions,  we  call  elements,  may 
be  susceptible  of  progressive  dissociation  at  enormously- 


MALLET’S  views. 


153 


high  temperatures,  and,  under  circumstances  in  which 
this  supposed  state  of  dissociation  admits  of  being  spectros- 
copically observed,  some  of  the  characteristic  features  in 
the  spectrum  of  what  is  usually  known  to  us  as  hydrogen 
become  in  a very  remarkable  degree  prominent.  If  such 
dissociation  may  really  occur,  and  if  the  atoms  of  hydro- 
gen may,  as  commonly  known  to  us,  form  either  the  last 
term,  or  any  term  not  far  removed  in  simplicity  from  the 
last,  in  the  progressive  breaking  up  of  other  forms  of 
matter,  it  is  obvious  that  “ Prout’s  law”,  or  some  modi- 
fication of  it,  such  as  was  many  years  ago  suggested  by 
Dumas,  must  be  true,  the  atomic  weights  of  all  the  other 
so-called  elements  must  be  multiples  of  that  of  hydro- 
gen or  multiples  of  that  fraction  of  the  hydrogen  atom 
which  may  result  from  the  dissociation  of  this  body  it- 
self. If  such  fraction  be  very  small  as  compared  with 
the  effect  of  the  inevitable  errors  of  experiment,  the  ex- 
perimental vertification  or  refutation  of  the  law  will  prove 
impossible,  but  if  it  be  considerable,  as,  for  instance,  one- 
half  of  the  commonly  known  hydrogen  atom,  or  one- 
fourth  as  assumed  by  Dumas,  the  question  admits  of 
practical  examination.” 

The  author  further  questioned  the  justice  of  the  view 
taken  by  Stas  of  his  results  that  ‘Prout’s  law’  is  dis- 
proved by  them  or  is  not  supported  by  them.  ‘ ‘The  care- 
ful work  of  Stas  and  others  only  proves  by  close  agree- 
ment of  the  results  that  fortuitous  errors  have  been  re- 
duced within  narrow  limits.  It  does  not  prove  that  all 
sources  of  constant  error  have  been  avoided  and  indeed 
this  can  never  be  absolutely  proved,  as  we  never  can  be 


154 


THE  PERIODIC  LAW. 


sure  that  our  knowledge  of  the  substances  we  are  deal- 
ing with  is  complete.” 

He  added  that,  of  course,  one  distinct  exception  to  the 
assumed  law  would  disprove  it,  if  that  exception  were 
itself  fully  proved,  but  this  is  not  the  case. 

‘‘Out  of  the  eighteen  best  known  atomic  weights  ten 
approximate  to  integers  within  a range  of  variation  less 
than  one-tenth  of  a unit.  The  degree  of  probability 
that  this  is  purely  accidental  is  found  to  be  only  equal 
to  i : 1097.8.  This  seems  to  illustrate  the  point  that 
not  only  is  Prout’s  law  not  as  yet  absolutely  over-turned, 
but  that  a heavy  and  increasing  weight  of  probability  in 
its  favor,  or  in  favor  of  some  modification  of  it,  exists 
and  demands  consideration.” 

108.  The  Views  of  Clarke. — In  his  Recalculation  of 
the  Atomic  Weights  (123),  Clarke  discussed  the  views 
expressed  by  Mallet. 

He  said  that  when  0=  16  is  taken  as  the  standard, 
forty  out  of  sixty-six  elements  whose  atomic  weights 
have  been  recalculated  by  him  fell  within  the  limit  of 
variation,  i.  e.,  one-tenth  of  a unit  variation  from  whole 
numbers,  and  twenty-six  fell  without.  These  he  ex- 
amined in  detail  and  concluded  that  none  of  the  seeming 
exceptions  are  inexplicable.  Some  of  them,  indeed, 
carefully  investigated,  support  it  strongly.  In  short,  ad- 
mitting half  multiples  as  legitimate,  it  is  more  probable 
that  the  few  apparent  exceptions  are  due  to  undetected 
constant  errors,  than  that  the  great  number  of  close  agree- 
ments should  be  merely  accidental.  “ I began  this  re- 
calculation of  the  atomic  weights  with  a strong  prejudice 


CROOKES  UPON  PROUT’S  HYPOTHESIS.  155 

against  Prout’s  hypothesis  but  the  facts  as  they  come  be- 
fore me  have  forced  me  to  give  it  a very  respectful  con- 
sideration. All  chemists  must  at  least  admit  that  the 
strife  over  it  is  not  yet  ended,  and  that  its  opponents 
cannot  therefore  claim  a perfect  victory.” 

109.  Crookes  upon  Prout’s  Hypothesis  : — In  his  ad- 
dress before  the  British  Association  (156)  he  said:  ‘‘But 
if  the  evidence  in  favor  of  Prout’s  hypothesis  in  its  ori- 
ginal guise  is  deemed  insufficient,  may  not  Mr.  Clarke’s 
suggestion  of  half  multiples  place  it  upon  an  entirely 
new  basis  ? Suppose  that  the  unit  of  the  scale,  the  body 
whose  atomic  weight,  if  multiplied  by  a series  of  whole 
numbers,  gives  the  atomic  weights  of  the  remaining  ele- 
ments, is  not  hydrogen  but  some  element  of  still  lower 
atomic  weight  ? We  are  here  at  once  reminded  of  he- 
lium, an  element  purely  hypothetical  as  far  as  our  earth 
is  concerned,  but  supposed  by  many  authorities,  on  the 
faith  of  spectroscopic  observations,  to  exist  in  the  sun 
and  other  stellar  bodies.  Most  solar  explosions  pre- 
sent merely  the  characteristic  lines  of  hydrogen,  C,  F, 
and  H,  and  along  with  them  one  particular  line  which 
at  first  was  classed  in  the  group,  but  which  is  a little 
more  refrangible  and  is  designated  by  the  symbol  Dz. 
According  to  Mr.  Norman  Bockyer  and  the  late  Father 
Secebi,  this  ray  undergoes  modifications  not  comparable 
to  those  affecting  other  rays  of  the  atmosphere.  In  the 
corresponding  region  of  the  spectrum  no  dark  ray  has 
been  observed.  That  the  accompanying  lines  C,  A'and 
//"pertain  to  hydrogen  is  evident  ; and  as  Dz  has  never 
been  obtained  in  any  other  spectrum  it  is  supposed  to 


THE  PERIODIC  LAW. 


156 

belong  to  a body  foreign  to  our  earth,  though  existing 
in  abundance  in  the  atmosphere  of  the  sun.  To  this  hy- 
pothetical body  the  name  helium  is  assigned.  In  an 
able  memoir  on  this  subject  read  before  the  Academy  of 
Brussels,  the  Abbe  E.  Spee  shows  that,  if  helium  ex- 
ists, it  enjoys  two  very  remarkable  properties.  Its 
spectrum  consists  of  a single  ray,  and  its  vapor  possesses 
no  absorbent  power.  The  simple  single  ray,  though  I 
believe  unexampled,  is  by  no  means  an  impossible  phe- 
nomenon, and  indicates  a remarkable  simplicity  of  mole- 
cular constitution.  The  non-absorbent  property  of  its 
vapor  seems  to  be  a serious  objection  to  a general  physi- 
cal law.  Professor  Tyndall  has  demonstrated  that  the 
absorptive  power  increases  with  the  complexity  of  molec- 
ular structure,  and  hence  he  draws  the  conclusion  that 
the  simpler  the  molecule  the  feebler  the  absorption. 
This  conclusion  the  Abbe  Spee  regards  as  perfectly  legi- 
timate : but  it  neither  explains  nor  even  necessitates 
the  absence  of  all  absorptive  power. 

“Granting  that  helium  exists,  all  analogy  points  to  its 
atomic  weight  being  below  that  of  hydrogen.  Here, 
then,  we  may  have  the  very  element,  with  atomic  weight 
half  that  of  hydrogen,  regarded  by  Mr.  Clarke  as  the 
basis  of  Prout’s  Eaw.’’ 

These  speculations  read  very  strangely  in  the  light  of 
our  later  knowledge  of  helium. 

no.  Meyer  and  Seubert  on  Prout’s  Hypothesis. — The 
authors  (147)  admit  that  in  Prout’s  Hypothesis  there 
may  be  a kernel  of  truth  concealed  but  maintain  still 
that  in  its  present  form  it  is  untenable. 


bayeey’s  arrangements. 


157 


Wherever  it  has  been  put  to  the  proof  by  accurate  de- 
termination it  has  been  shown  that  these  atomic  weights 
are  not  exact  integers  or  multiples  and  this  is  independ- 
ent of  the  ratio  of  oxygen  to  hydrogen. 

The  authors  note  that  the  atomic  weights  of  more  than 
the  fourth  part  of  all  elements  are  nearly  exact  multiples 
of  the  half-atom  or  the  equivalent  of  oxygen.  Such  reg- 
ularities are  worthy  of  note  but  to  rectify  the  atomic 
weights  by  means  of  them  would  be  as  inadmissable  as 
the  rounding  of  fractions  into  whole  numbers. 

in.  Groshanson  Prout’s  Hypothesis. — Groshans  con- 
sidered (188)  this  hypothesis  with  special  reference  to 
the  atomic  weights  of  carbon  and  oxygen. 

The  author  showed  that  isomeric  organic  compounds, 
containing  carbon,  hydrogen  and  oxygen,  which  have 
the  same  molecular  weight  but  different  composition,  be- 
long to  one  of  seven  general  series,  the  molecular 
weights  in  each  of  which  are  given  by  1 \n  -f-  2x  where 
x is  any  unit  less  then  seven.  He  argued  from  the  equal- 
ity in  the  molecular  weights  of  such  compounds  of  differ- 
ent composition,  that  the  atomic  weights  differed  by  some 
multiple  of  that  of  hydrogen,  so  that  C-(-4=0  and 
4C  = Oa  and  hence  that  C = 12  and  O = 16. 

112.  Bay  ley’s  Attempt  at  Showing  the  Connection 
between  the  Atomic  Weights  and  the  Other  Properties 
of  the  Elements. — In  a communication  to  the  Philo- 
sophical Magazine  in  1882,  Thomas  B.  Bayley  ( 124)  tried 
to  show  the  connection  between  the  atomic  weights  and 
the  properties  of  the  elements.  He  followed  the  arrange- 


158  THE  PERIODIC  LAW. 

ment  in  the  order  of  the  atomic  weights  and  took  note 
of  the  periodic  recurrence  of  the  same  group  of  proper- 
ties in  sets  of  seven.  He  distinguished  between  the  de- 
gree of  relationship  in  the  various  groups  and  families 
and  divided  the  elements  into  cycles,  series  and  indivi- 
duals. A reference  to  his  table  will  give  an  idea  of  the 
plan  of  his  arrangement. 

C* 

f a\ 

5 

b- 


f 

. d- 

.7 

The  main  family  of  all  the  groups  isl.ai;  II. ai;  Ill.ai; 
IV. ^i;  V.ai ; and  with  this  the  groups  are  connected  as 
follows  : 


fi 

I 2 


fi 

2 

'1 

2 

4 

5 

6 

3 

3 

n 

■ 4 II.  a- 

4 HI. -I 

i 

IV-- 

5 

5 

2 

6 

6 

.7 

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3 

4 

5 

6 

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a\ 


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2 

3 

4 

I 5 

I 6 

17 

fi 

2 

3 

4 

5 

6 

17 


ONCn  M h m ONCn  K)  HVJ  <J\Ln  C*»  fO 


GLADSTONE’S  ADDRESS. 


159 


III.  ax—  IV.  fli — V.  ai 


\ 


III.  bi — IV.  bi— V.  di 


By  this  method  each  element,  whether  known  or  un- 
known, is  represented  by  a symbol  expressing  its  posi- 
tion with  regard  to  the  other  elements  and  its  relation  to 
these,  whether  axial,  as  among  the  members  of  a family, 
or  lateral,  as  between  adjacent  elements  in  a series  or 
cycle.  The  following  circumstances  are  connected  with 
the  properties  of  an  element. 

a.  The  position  or  sequence  in  a series. 

b.  The  proper  position  in  the  series. 

c.  The  position  in  a cycle. 

Bayley  also  gave,  in  a diagram  like  that  of  Meyer, 
the  curves  obtained  by  taking  the  atomic  weights  as  or- 
dinates and  plotting  out  the  atomic  volumes  and  other 
properties  as  abscissae.  His  diagram  with  the  elements 
filled  in  at  their  proper  places  is  reproduced,  in  connec- 
tion with  an  article  of  Carnelley. 

1 13.  Gladstone’s  Address  before  the  British  Associa= 
tion. — The  question  as  to  the  possibly  composite  nature 
of  the  chemical  elements  was  taken  up  by  Gladstone,  at 
the  meeting  of  the  British  Association  in  1882.  He  first 
gave  (131)  a very  interesting  account  of  the  various  ideas 
and  theories  as  to  the  primal  elements  held  by  the  dif- 
ferent ancient  peoples  and  alchemists. 

The  question  as  to  whether  the  elements  known  to  the 
chemist  at  present  are  to  be  considered  simple  undecom- 


i6o 


THE  PERIODIC  LAW. 


posable  bodies  or  not,  he  approached  from  three  “ points 
of  attack.” 

I.  The  spectroscope.  It  was  hoped  that  by  finding 
identical  rays  in  spectra  of  different  elements  a common 
constituent  might  be  proved  to  be  present.  A certain 
similarity  has  been  observed  but  not  identity.  This  is 
negative  but  not  fatal  to  the  idea  that  the  elements  are 
compounds  for  it  is  known  that  the  spectrum  of  a com- 
pound is  not  made  up  of  the  spectra  of  its  components. 

Again  the  multiplicity  of  rays  given  out  by  some  ele- 
ments might  point  to  a complex  constitution.  Still  this 
may  be  merely  complexity  of  arrangement.  Lastly, 
spectroscopic  work  upon  the  sun  has  shown  some  re- 
markable phenomena.  The  explanation  of  these,  how- 
ever, is  not  clear  as  yet. 

II.  The  composite  nature  of  the  elements  might  be  in- 
ferred from  certain  peculiar  regularities  in  the  atomic 
weights.  Here  Gladstone  discussed  the  work  of  Dumas, 
Newlands  and  Mendeleeff. 

III.  From  specific  refraction.  Here  we  find  that  light 
is  acted  upon  very  differently  by  these  groups  of  ele- 
ments and  by  the  compound  radicals  and  the  organic 
homologous  series  of  hydrocarbons.  The  elementary 
radicals,  if  they  are  such,  are  essentially  different  from 
the  compound  radicals  though  their  chemical  functions 
are  similar. 

“ The  remarkable  relations  between  the  atomic  weights 
of  the  elements  and  many  pecularitiesof  their  grouping, 
force  upon  us  the  conviction  that  they  are  not  separate 


hartley’s  criticism  of  lockyer. 


161 


bodies  created  without  reference  to  one  another,  but  that 
they  have  been  originally  fashioned,  or  have  been  built 
up  from  one  another,  according  to  some  general  plan.” 

1 14.  Hartley  on  Spectroscopic  Evidence  as  to  the  Na= 
ture  of  the  Elements. — With  regard  to  the  evidence  to  be 
gotten  from  the  spectroscope,  Hartley  (128,  129)  wrote  : 
‘‘There  is  evidently  a harmonic  relation  between  the 
lines  in  the  spectra  of  magnesium,  zinc,  cadmium,  alum- 
inium and  in  those  of  calcium,  strontium  and  barium, 
when  two  octaves  of  the  spectrum  are  examined.  This 
extension  to  two  octaves  is  possible  by  means  of  photo- 
graphs. The  fundamental  vibrations  appear  to  be  all  in 
the  infra-red  region. 

“ In  order  that  harmonic  relations  between  lines  and 
groups  of  lines  may  be  rendered  apparent  it  is  neces- 
sary to  map  spectra  according  to  their  oscillation  frequen- 
cies instead  of  wave  lengths.” 

The  author  has  thus  mapped  the  wave  frequencies  in 
one  mm.  of  the  chief  rays  in  the  spectra  of  Mg,  Zn,  Cd, 
Cu,  A g,  Si,  B,  and  Al.  The  data  thus  obtained  support 
the  view  that  elements  whose  atomic  weights  differ  by  a 
constant  quantity  and  whose  chemical  character  is  simi- 
lar, are  truly  homologous  or  in  other  words  are  the  same 
kind  of  matter  in  different  states  of  condensation. 

1 15.  Hartley’s  Criticism  of  Lockyer. — Hartley  also 

criticized  the  work  of  Lockyer : ‘ ‘ It  will  be  remembered 

that  Mr.  Norman  Lockyer  has  proposed  to  explain  the 
occurrence  of  several  coincident  lines  in  the  spectra  of 
different  elements  by  supposing  that  each  spectrum  is 


162 


THE  PERIODIC  LAW. 


composed  of  several  spectra,  and  that  these  compound 
spectra  are  the  spectra  of  compound  bodies  and  not  of 
elements.  The  action  of  a low  temperature  causes  the 
vibration  of  a compound  molecule,  while  the  action  of  a 
high  temperature  causes  a breaking  up  of  the  molecule 
either  into  smaller  molecules  of  the  same  element,  or  in- 
to those  of  distinct  elements.  It  appears  also  from  the 
way  in  which  he  has  treated  the  subject,  that  every  ele- 
mentary substance  may  be  decomposed  into  as  many 
simple  substances  as  there  are  rays  in  its  spectrum.  I 
allude  here  to  the  observations  concerning  the  lines  in 
the  spectra  of  iron,  calcium,  magnesium,  lithium,  and  hy- 
drogen. M.  Lecoq  de  Boisbaudran,1  also  Vogel2  and 
von  Monckhoven3  have  disposed  of  some  of  these  facts 
upon  which  this  theory  is  founded.  With  even  very 
moderate  dispersive  power,  something  like  1200  lines 
can  be  recognized  in  the  spectrum  of  iron,  an  element 
which  has  an  atomic  weight  of  56,  and  it  is  simply  incon- 
ceivable that  a body  of  the  chemical  nature  of  iron  can 
have  a molecular  structure  so  complex  as  to  be  composed 
of  1200  different  simpler  substances.  Mr.  Lockyer’s  hy- 
pothesis seems  quite  incompatible  with  the  theory  that 
the  spectra  are  composed  with  harmonic  vibrations,  be- 
cause a compound  body  would  give  two  or  more  series 
of  harmonics  related  to  two  or  more  fundamental  vibra- 
tions, and  elements  having  a common  component  should 
give  spectra  in  which  the  same  series  or  groups  of  lines 
should  appear.  If,  therefore,  we  are  to  draw  inferences 


1 Compt.  rend.,  73,  943;  and  82,  1264. 

2 Ber.,  13,  274. 

8Compt.  Rend.,  90,  520, 


LAURIE  ON  THE  PHYSICAL  PROPERTIES.  163 

as  to  the  compound  nature  of  substances  from  coincident 
lines  in  their  spectra,  it  is  not  single  lines  but  harmonic 
series  that  we  must  look  to  for  coincidences. 

“It  is  upon  there  currence  of  such  groups  of  lines  that 
Ciamician  (118)  has  based  his  conclusion  that  silicon  is 
composed  of  carbon  and  oxygen,  with  a corresponding 
weight  12,  16,  28,  and  aluminium,  of  boron  and  oxygen, 
11,  16,  27.” 

116.  The  Numerical  Relations  of  Fedaroff. — Fedaroff 
(127)  has  discovered  a somewhat  obscure  and  yet  sin- 
gular relation  between  the  atomic  weights.  He  gives  a 
table  in  which  the  elements  are  placed  in  an  ascending 
series  with  a uniform  difference  of  0.5.  This  table  fol- 
lows on  p.  164. 

If  the  numbers  in  these  tables  be  raised  to  the  power 
f and  the  result  be  multiplied  by  f-  one  will  obtain  ap- 
proximately the  atomic  weights  of  the  elements.  Ad- 
mitting the  homogeniety  and  similarity  of  the  atoms, 
one  must  conclude,  according  to  the  author,  that  the  ele- 
ments are  arranged  in  the  natural  system  in  arithmet- 
ical progression  increasing  with  the  surface  of  their  atoms. 
In  Group  VIII.,  for  example,  the  ratio  of  the  atomic 
surfaces  are  as  4,  6,  9,  whilst  the  surfaces  of  Cl,  Br,  and  I 
are  as  3,  5,  7.  The  atomicity  and  general  chemical 
properties  of  the  elements  are  essential  functions  of  these 
surfaces. 

117.  Laurie  on  the  Physical  Properties. — Laurie 
(132)  has  been  a valuable  investigator  in  the  direction 
of  the  extension  of  the  Periodic  Law  along  the  lines  of 
the  physical  properties.  One  of  his  more  important  pa- 


164 


THE  PERIODIC  DAW 


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< Ph 

n-. 

miles’  equation  for  atomic  weights.  165 


pers  was  upon  the  relations  between  the  heats  of  combina- 
tion of  the  elements  and  their  atomic  weights. 

1 18.  Gerber’s  Modification  of  the  Hypothesis  of  Prout. 

— Gerber  (133)  has  so  modified  the  Proutian  hypothe- 
sis that  a discussion  of  it  comes  quite  properly  under  the 
heading  of  the  general  numerical  relations.  According 
to  him  all  the  atomic  weights  are  simple  multiples  of  one 
of  the  four  following  numbers  : di  — 0.769 ; = 1.995  > 

d3=  1.559;  d4  = 1.245.  The  monatomic  elements  are 
multiples  of  d1 ; the  tetratomic,  the  alkaline  earths,  and 
the  elements  related  to  C and  O are  multiples  d s ; the 
triatomic  and  pentatomic  of  d3 ; and  the  metals,  in  a nar- 
rower sense,  of  dt.  Between  these  four  numbers  the  fol- 
lowing relation  can  be  seen  : dl:d2\d3  \ d^.:^ : 2 : (f)2  : f . 

119.  Mill’s  Equation  for  Calculating  the  Atomic 
Weights. — Mills  (137)  in  a discussion  of  the  melting 
and  boiling  points  as  related  to  chemical  composition 
showed  that  the  atomic  weights  may  all  be  expressed  by 
the  equation 


Where  n~  15  ; p aperiodic  or  group  number  and  x is 
an  ordinal  integer.  From  this  formula  he  calculated  the 
atomic  weights  and  found  a close  correspondence  with 
the  observed  numbers.  The  author  then  discussed  the 
genesis  of  the  elements  on  a theory  of  gradual  cooling, 
using  the  analogy  of  iodine;  sulphur  ; phosphorus  and 
its  allotrophic  form  ; NO  and  N20,,  etc. 

He  further  gave  a classification  of  the  elements,  de- 


i66 


THE  PERIODIC  LAW. 


fining  an  element  as  one  of  a list  of  complex  simple  sub- 
stances whose  numerics  are  of  the  form _y=(  1.2.3.  ... ) 
15 — 15  (.9375)!  A table  is  given  based  on  this.  He  re- 
garded As,  Sb,  probably  Er  and  perhaps  Os  as  the  only 
known  polymers  of  primitive  matter. 

His  method  of  tabulation  made  it  possible  for  the 
number  of  the  elements  to  be  infinite  but  the  methods  of 
discovery  are  not  infinite  and  he  thought  few  more  would 
be  discovered  unless  by  a new  method  or  a new  combina- 
tion of  methods. 

120.  Carnelley’s  Study  of  the  Relations  of  Physical 
Properties. — Carnelley,  who  has  done  much  to  extend 
the  Periodic  Eaw,  and  was  singled  out  above  all  others 
by  Mendeleeff  as  having  aided  in  its  development,  pub- 
lished in  1884  a paper  (138)  in  which  he  considered 
especially  the  melting  and  boiling  points  and  the  heats 
of  formation.  First  he  examined  these  properties  for  the 
halogens  and  established  for  them  the  correctness  of  the 
Periodic  Eaw.  From  this  he  went  further  to  the  calcula- 
tion of  unknown  melting  and  boiling  points  and  then 
showed  how  the  knowledge  of  these  properties  would 
enable  one  to  determine  the  atomic  weight  of  an  element, 
and  could  in  fact  be  used  in  the  place  of  the  vapor  density 
and  the  specific  heat  when  these  failed  to  give  satisfactory 
results.  The  position  of  an  element  in  the  table  could 
also  be  determined  by  the  use  of  the  same  properties. 
Many  tables  and  a diagram  accompany  the  article. 

121.  The  New  Law  of  Qroshans. — Groslians  (141) 
announced  in  1882  what  he  called  the  New  Law  : 


PELOPIDAS’  comparison  with  radical.  167 

“ The  specific  weights  of  bodies  measured  at  the  tem- 
perature of  the  boiling  point  or  any  corresponding  tem- 
peratures, are  proportional  to  their  density  numbers. 
Each  element  has  a density  number.  Thus  for  C,  H, 
and  O it  is  1,  for  S it  is  2,  for  N,  3,  etc.” 

In  a later  paper  (144)  the  author  made  use  of  this 
law  to  bring  out  the  connection  between  the  specific 
gravities  and  the  atomic  weight  periods. 

122.  Pelopidas  Compares  the  Elements  with  the  Or= 
ganic  Radicals. — Pelopidas  ( 134)  showed  in  1883  that,  as 
the  elements  are  ordered  by  rising  atomic  weights  in  the 
periodic  system,  so  the  hydrocarbon  radicals  and  the 
nitrogenous  organic  radicals  can  be  arranged  in  defi- 
nite series,  in  periods,  in  accordance  with  their  composi- 
tion. In  these  periods  is  to  be  seen  also  a repetition  and 
a gradual  transition  of  properties  of  the  individual  mem- 
bers of  a period.  Also  the  number  of  members  or  of 
radicals  of  each  period  is  just  as  large  as  that  of  the  ele- 
ments in  a period  of  the  natural  system.  Thus,  for  in- 
stance, in  the  compound  ammonium  or  alcohol  radicals 
CnH2n  + I a transition  to  acid  radicals  is  found. 

If  one  places  in  the  first  group  with  Na  the  alcoholic 
tetra-ammonium  radical  N (CnH2  „ + I)torN  CmH2  m + 4 and 
derives  the  remaining  groups  by  a gradual  reduction  of 
the  amount  of  hydrogen,  one  gets  in  the  seventh  group  a 
radical  of  the  composition  NCmH2  m_2  whose  representa- 
tive would  be  cyanogen  which  is  a genuine  analogue  of 
Cl  and  F.  The  following  example  is  also  given  : 

i.  cnH2Q+I.  11.  c„h2„.  hi.  cnH2n_„  iv.  cbh,m. 

V.  C„H2 n_3.  VI.  CnH2n_4.  VII.  CnH2n_5.  VIII.  CnH2n_6. 


i68 


THE  PERIODIC  LAW. 


According  to  this  one  returns  at  the  end  of  the  groups 
to  the  first  group  radical  or  CnH2n_7,  or  the  benzene  radi- 
cal. If  alcoholic  radicals  are  the  first  members  of  the 
series  then  acid  radicals  are  the  last  and  these,  like  the 
corresponding  elements,  are  in  position  to  form  higher 
oxidation  steps.  Thus,  for  instance,  the  radical  of  the 
sixth  group  will  give  an  hydroxide  RHa04  or  CnH2n_4, 
H204  or  CnH2n_204.  This  formula  can  only  be  looked 
upon  as  an  expression  for  the  composition  of  the  homo- 
logues  of  oxalic  acid. 

123.  The  Spiral  of  von  Huth. — Ernst  von  Huth  (143) 
gave  in  1 884  a diagram  to  illustrate  the  Periodic  Eaw.  He 
made  use  of  the  spiral,  as  had  already  been  done  by  Bauin- 
hauer  and  in  a measure  by  Hinrichs.  The  spiral  was  con- 
structed as  follows.  From  a common  centre  seven  radii 
diverge  and  on  these  are  placed  the  atomic  weights  be- 
ginning with  the  least.  Thus  all  of  the  elements  of  one 
group  will  fall  upon  the  same  radius.  Lithium  is  placed 
on  the  first  radius  at  a distance  of  seven  mm.  then  fol- 
lows Be  on  the  next  at  a distance  of  nine  mm.  Some- 
times, as  for  Fe,  Co,  and  Ni,  instead  of  one  element 
several  are  placed  on  the  same  line  at  once. 

2.  In  each  line,  or  family,  two  distinct  groups  of  ele- 
ments may  be  distinguished  by  taking  alternate  elements 
beginning  with  the  second  or  third  member.  The  begin- 
ning members  of  each  family  have  a special  position 
peculiar  to  them  and  also  an  intermediate  position  be- 
tween the  chief  groups. 

3.  The  distance  between  the  members  of  every  group 
is  subject  to  a distinct  periodicity,  thus  ; 


\ F fyr 


2,nd  Radius 


bertheeot’s  ideas  as  to  primae  matter.  169 

Lithium  family.  16-16-24-22-23-25-63. 

Beryllium  family.  15-16-28-22-25-25-63. 

So  too  we  have  the  differences  in  the  O and  N families  : 

Oxygen  family.  16-21-25-18-29-59-56. 

Nitrogen  family.  17-20-26-19-28-60-?. 

4.  The  table  is  intended  also  to  show  valence  and 
chemical  behavior  as  functions  of  the  atomic  weights. 

5.  The  specific  gravities  stand  in  a peculiar  relation 
to  the  atomic  weights. 

6.  Related  groups  of  elements  seem  to  possess  homolo- 
gous spectra;  other  properties  are  also  mentioned. 

124.  Berthelot’s  Ideas  as  to  Primal  Hatter. — Berthe- 
lot  (145)  gave  in  “Res  Origines  de  l’Alchimie,”  after 
his  criticism  of  the  periodic  system  of  Mendeleeff,  his 
own  ideas  as  to  the  constitution  of  matter  and  the  pri- 
mal matter.  La  critique  est  facile  mais  V art  est  difficile. 

“ The  fundamental  identity  of  the  matter  contained  in 
the  chemical  elements  and  the  possibilities  of  transmuta- 
tion among  these  reputed  simple  bodies  may  be  admitted 
as  very  plausible  hypotheses  without  the  existence  of  a 
unique  form  of  matter,  capable  of  isolation,  resulting 
from  them.  One  of  these  hypotheses  does  not  carry  the 
other  as  necessary  sequence  although  this  has  been  the 
view  held  up  to  the  present.  This  merits  particular  at- 
tention. 

“ In  truth,  in  admitting  the  unity  of  matter  as  estab- 
lished it  is  conceived  that  the  matter  is  one  suscep- 
tible of  a certain  number  of  states  of  stable  equilibrium, 
beyond  which  it  will  not  be  manifested.  The  sum  of 
these  stable  states  will  form  the  simple  bodies  known  to- 


THE  PERIODIC  LAW. 


17O 

day  and  the  simple  bodies  which  will  be  discovered  one 
day  and  even  formed  synthetically,  supposing  that  one 
should  ever  attain  to  the  discovery  of  the  law  of  genera- 
tion. But  one  has  always  reasoned  by  comparing  these 
multiple  states  of  equilibrium  of  that  matter  with  the 
actual  compounds  formed  by  the  addition  of  simpler  ele- 
ments. 

‘ ‘ Still  these  matters  can  be  thought  of  in  an  entirely 
different  manner.  It  is  possible  that  the  diverse  states 
of  equilibrium  in  which  the  fundamental  matter  manifests 
itself  are  neither  buildings  made  up  by  the  addition  of 
different  elements,  nor  buildings  made  up  by  the  addi- 
tion of  identical  elements  but  unequally  condensed.  In 
a word,  it  does  not  appear  necessary  that  all  these  molec- 
ular buildings  should  represent  the  entire  multiples  of 
a small  number  of  ponderable  elementary  units.  One 
can  just  as  well  fancy  that  such  edifices  offer,  the  one  by 
correspondence  with  the  other,  the  generating  relations 
of  another  order:  such,  for  instance,  as  the  relations 
existing  between  the  geometric  symbols  of  the  different 
roots  of  an  equation,  or  more  generally  between  the 
multiple  values  of  one  function  defined  by  mathematical 
analysis.  The  fundamental  matter  would  represent  then 
the  generating  function  and  the  simple  bodies  would  be 
the  determined  values.  * * * 

“According  to  this  hypothesis,  a reputed  simple  body 
can  be  destroyed  but  not  decomposed  in  the  ordinary 
sense  of  the  term.  At  the  moment  of  its  destruction  the 
simple  body  is  instantaneously  transformed  into  one  or 
more  other  simple  bodies,  identical  or  analogous  to 


CARNELLEY  ON  THE  PERIODIC  LAW.  171 

actual  elements.  But  the  atomic  weight  of  the  new  ele- 
ments could  not  show  a commensurable  relation  to  the 
atomic  weight  of  the  primitive  body  which  will  be  pro- 
duced by  its  metamorphosis. 

“According  to  this  view,  the  body  which  would  re- 
sult by  the  metamorphosis  of  any  one  of  the  elements 
ought  not  to  be  regarded  as  a simple  body  by  comparison 
with  it. 

“The  different  simple  bodies  can  be  made  up  of  the 
one  matter  distinguished  only  by  the  nature  of  its  motions. 
The  transmutation  of  an  element  will  not  then  be  any- 
thing more  than  the  transformation  of  the  movements 
which  correspond  to  the  existence  of  that  element  and 
which  communicate  to  it  its  peculiar  properties,  in  these 
specific  movements  corresponding  to  the  existence  of 
another  element.”  Berthelot  says  that  these  specula- 
tions were  presented  before  the  Societe  Chimique  de 
Paris  in  1863. 

125.  Carnelley  on  the  Periodic  Law  and  the  Occurrence 
of  the  Elements. — The  author  began  his  paper  (140)  by 
commenting  upon  the  work  of  Gladstone.  “Gladstone 
(Phil.  Mag.  (5)  IV  p.  379.)  has  proposed  to  account 
for  the  occurence  of  elements  as  to  degree  of  distribution. 

‘ ‘ Gladstone  divides  them  into  ( 1 ) plentiful,  ( 2 ) common, 
(3)  rare,  (4)  very  rare,  and  shows  that  the  average  vapor 
densities  of  the  first  class  are  less  than  the  second,  the  sec- 
ond than  the  third,  etc.,  concluding  that  elementshaving 
least  vapor  densities  tended  to  remain  more  towards  the 
surface  during  the  period  of  the  earth’s  formation,  whilst 
elements  having  a high  vapor-density  accumulated  more 


172 


THE  PERIODIC  LAW. 


toward  the  center  and  hence  occur  but  rarely  on  the  sur- 
face.’’ He  then  referred  to  the  fact  that  Mendeleeff  has 
shown  that  elements  with  small  atomic  weights  are  the 
most  abundant.  He  considered  then  in  connection  with 
the  Mendeleeff  table  : 

1.  Reducibility  of  the  elements,  (elements  belonging 
to  the  odd  series  more  easily  reducible)  : 

2.  Occurence  in  the  free  state  : 

3.  Ocurrence  in  the  compound  state  : 

He  then  expressed  the  facts  in  terms  of  Lothar  Meyer’s 
curve  of  the  elements. 

126.  Carnelley  on  the  Cause  of  the  Periodic  Law. — 

Carnelley’s  paper  (150)  read  before  the  Aberdeen  meet- 
ing of  the  British  Association  in  1885,  suggesting  a cause 
for  the  periodic  law,  used  chiefly  analogies  drawn  from 
organic  chemistry.  As  we  have  seen,  these  analogies 
have  been  frequently  called  into  aid  before  in  solving  this 
problem  and  we  will  come  upon  a number  of  other  papers 
based  upon  them. 

Carnelley  argued  the  compound  nature  of  the  elements 
from  the  analogy  to  the  hydrocarbons  or  alcohol  radi- 
cals. He  summed  up  his  previous  work. 

1.  His  first  paper  dealt  with  a comparison  of  the 
melting  and  boiling  points  and  heats  of  formation  of 
the  normal  halogen  compoundsof  the  elements  and  it  was 
shown  that  relationships  existed  between  them,  depend- 
ing upon  the  atomic  weight  of  both  the  positive  element 
and  the  halogen. 

2.  The  second  paper  dealt  in  a similar  manner 
with  some  of  the  physical  properties  of  the  normal  alkyl 


carneeeey  on  the  periodic  daw.  173 

compounds  of  the  elements  and  the  same  relationships 
were  observed. 

3.  The  third  paper  showed  that  normal  halo- 
gen and  normal  alkyl  compounds  of  the  hydrocarbon 
radicals  exhibit,  with  one  exception,  relationships  simi- 
lar to  those  of  the  corresponding  compounds  of  the  ele- 
ments. From  these  he  inferred  : 

“ That  the  elements,  as  a whole,  are  analogous  to  the 
hydrocarbon  radicals,  having  a similar  function  in  their 
several  compounds  and  most  probably  a somewhat  simi- 
lar chemical  constitution  or  they  are  analogous  in  both 
form  and  function.” 

A very  full  and  exhaustive  comparison  was  given  in 
tables  and  in  diagrammatic  curves  to  illustrate  and  prove 
the  above  assumption.  He  gave  two  large  diagrams 
showing  the  division  of  elements  and  hydrocarbons  into 
groups  and  also  their  evolution. 

In  his  general  conclusions,  he  drew  the  further  in- 
ference : ‘‘That  the  elements  are  not  elements  in  the 
strict  sense  of  the  term,  but  are  in  fact  compound  radi- 
cals, made  up  of  at  least  two  simple  elements,  A and  B.” 
A system  of  elements  built  up  in  this  way  should  fulfill 
the  following  conditions. 

1.  They  must  be  capable  of  division  into  series  and 
groups,  that  is  to  say,  they  must  exhibit  periodicity. 

2.  The  several  series  must  run  in  octaves. 

3.  Some  feature  corresponding  to  ‘‘odd  and  even 
series”  must  be  exhibited. 

4.  The  atomic  weights  must  increase  across  the  sys- 


174 


THE  PERIODIC  LAW. 


tem  from  the  first  to  the  seventh  group,  from  the  positive 
to  the  negative  end  of  each  series. 

5.  The  atomicity  must  increase  from  the  first  to  the 
fourth,  or  middle  group,  and  then  either  increase  or 
diminish  to  the  seventh. 

6.  It  should  exhibit  some  feature  corresponding  to  the 
eighth  group  in  Mendeleeff’s  table  of  the  elements. 

7.  The  atomic  weights  in  such  a system  should 
coincide  with  or  approximate  to  the  commonly  received 
atomic  weights  of  the  elements.  The  table  wdiich  he 
appended  does  not  rigorously  accord  with  all  these  condi- 
tions. Indeed  it  could  hardly  be  expected  that  it  would 
since  he  insisted  on  copying  the  defects  of  Mendeleeff’s 
table  as  well  as  its  more  valuable  features.  He  made 
use  of  Bayley’s  table  slightly  modified.  The  table  re- 
quires the  assumption  of  an  element  of  negative  atomic 
weight,  namely  B = — 2.  There  is  a difference  between 
the  observed  and  calculated  weights,  though  not  a very 
large  one.  All  of  the  weights  are  even  numbers  which 
of  course  makes  a very  striking  variation  from  the  actual 
weights  of  the  elements.  He  omitted  a few  elements  such 
as  Ag,  Au  and  Fe  since  their  proper  places  are  not  wTell 
known. 

As  to  the  structure  of  the  system  : 

First.  The  binary  elements  (except  Ti,  V,  Cr,  and  Mn) 
which  would  be  represented  by  the  formula  AnB2a-\-  (4-x) 
may  all  be  represented  by  the  general  formula  AnB2n-\~ 
(2 — x),  in  which  A = 12  and  B—  2,  whilst  x = ;«th 
group  — (—  wth  homologous  series  to  wThich  any  element 
belongs.  A is  supposed  to  be  a tetrad  element  identical 
with  carbon,  and  B a monad  element. 


I 


DiPf-  DiPR  DiFR  DiF* 

V6.3  Rb  &S3  y.5  Cs  me  — — Monads  Group 


spring’s  diagram  of  the  elements.  177 

Second.  The  atomic  weights  are  all  even  integers. 
This  is  due  to  the  value  of  B which  has  been  for  the 
sake  of  simplicity  taken  as  equal  to — 2 whereas  its  value 
should  lie  between — 1.99  and — 2.0. 

Third.  The  difference  between  odd  and  even  series  is 
here  the  difference  between  saturated  and  unsaturated 
binary  elements. 

Fourth.  The  difficulty  seen  in  subtracting  the  atomic 
weight  of  a negative  element  as  B from  positive  A could 
be  obviated  by  substituting  DB 4 for  A where  D is  a hep- 
tavalent  element  of  the  atomic  weight  20. 

Fifth.  This  system  would  admit  of  isomeric  elements. 

Sixth.  The  elements  are  all,  except  hydrogen,  sup- 
posed to  be  composed  of  two  simpler  elements,  viz. ,. 
A=i2  and  B— — 2.  Of  these  A is  identical  with  the  ele- 
ment carbon  whilst  B is  a substance  of  negative  weight 
possibly  the  ethereal  fluid  of  space. 

“If  the  theory  be  true,  then  it  is  interesting  to  observe 
that  whereas  the  hydrocarbons  are  compounds  of  carbon 
and  hydrogen,  the  chemical  elements  would  be  com- 
pounds of  carbon  with  ether  ( atomic  weight  equal  to  — 2 ) , 
the  two  sets  of  bodies  being  generated  in  an  exactly 
analogous  manner  from  their  respective  elements.  There 
would  hence  be  the  primitive  elements  carbon,  hydrogen 
and  ether.  Two  tables  are  given  showing  this  genera- 
tion of  the  elements. 

127.  Spring’s  Diagram  of  the  Elements. — In  1881, 
Professor  W.  Spring,  ( 1 1 9) , of  the  University  of  Uiege, 
prepared  a diagram  of  the  elements  for  the  use  of  his 


Diagram  of  W.  Spring. 


SPRING’S  diagram  of  the  elements.  179 

students.  This  was  reproduced  in  the  form  of  a large 
lithograph,  without  accompanying  notes.  It  resembles 
the  diagram  of  Gibbesand  is  the  precursor  of  those  of 
Reynolds  and  Crookes.  It  is  given  on  page  178. 


CHAPTER  VII. 


THE  DEVELOPMENT  OF  THE  NATURAL  LAW. 

1885-1890. 

It  is  impossible  to  give  any  general  characterization 
of  this  period.  The  work  included  in  it  is  of  very  vary- 
ing degrees  of  importance  and  interest  and  is  not  along 
any  special  line.  We  find  again  numerical  relations 
mentioned,  usually  of  a more  abstruse  nature  than  those 
which  have  been  recorded  in  the  earlier  periods. 

There  is  much  which  shows  a trend  of  thought  to- 
ward the  theory  of  the  unity  of  matter  and  the  composite 
character  of  the  elements.  The  most  important  papers 
of  the  period  are  those  of  Reynolds,  Crookes,  Griin- 
wald,  and  the  Faraday  Lecture  of  Mendeleeff. 

128.  Rydberg  on  the  Nature  of  the  Periodicity. 

— Rydberg  published  in  the  years  1885  and  1886  two 
papers,  the  first  upon  the  periodic  system  and  its 
graphic  representation  and  the  second  upon  the  laws  of 
the  atomic  weights,  in  which  he  attempted  to  bring  out 
some  new  relations  and  to  solve  the  mystery  of  the  con- 
nection between  these  constants. 

The  author  observed  in  his  first  paper  (151)  that 
while  it  is  generally  agreed,  from  the  investigations 
of  Mendeleeff  and  Meyer,  that  the  properties  of  the 
elements  are  periodic  functions  of  their  atomic  weights, 
no  attempts  so  far  have  been  made  to  determine 
the  nature  of  these  functions.  It  is  necessary  to 
form  the  curves  of  these  properties  as  has  been  done 


1 82 


THE  PERIODIC  LAW. 


by  Lothar  Meyer  for  the  atomic  volumes.  This  curve  of 
Meyer  was  discussed  by  Rydberg  and  curves  for  the  speci- 
fic gravities,  etc.,  were  constructed  and  conclusions  drawn 
from  them.  His  general  conclusions  were  that  these 
curves  show  clearly  that  it  is  only  the  atomic  weight 
and  nothing  else  which  governs  the  specific  gravities 
and  melting  points  as  well  as  expansion  coefficients,  re- 
fraction equivalents  and  in  short  all  the  known  physical 
properties  of  the  elements.  To  state  it  more  explicitly: 

1.  The  physical  characteristics  of  the  chemical  ele- 
ments are  functions  of  their  atomic  weights. 

2.  These  functions  are  sums  total  of  a non-periodic 
and  a periodic  part. 

3 . The  periodic  part  is  the  function  of  a series  of  single 
periodic  functions  with  variable  amplitude,  whose  periods 
are  sub-multiples  of  that  of  the  first  one,  i.  e.,  are  re- 
lated as  a base  tone  to  its  harmonic  upper  tone. 

As  to  the  chemical  nature  of  the  element,  he  concluded 
that  two  atoms  of  the  same  element  attract  each  other 
with  a force,  the  strength  of  which  is  aperiodic  function 
of  the  atomic  weight. 

1.  Between  atoms  of  the  same  element  act  forces  of 
two  different  kinds,  non-periodic  and  periodic  functions 
of  the  atomic  weights. 

2.  The  non-periodic  force  seems  to  increase  continu- 
ously with  the  atomic  weight  and  follows,  at  least  for 
the  greater  distance,  Newton’s  Law  ; it  is  always  attrac- 
tive. 

3.  The  periodic  variable  forces  correspond  to  the  terms 
in  the  function  of  the  specific  gravity  and  have  the  same 


NATURE  OF  THE  PERIODICITY.  1 83 


Rydberg’s  Table  of  the  Atomic  Weight  Differences. 


II— I. 

hi— 11. 

IV— III. 

V— IV. 

VI— V. 

VII— VI. 

2 

Be — Li 
2.07 

B— Be 
1.82 

C— B 
1.07 

N— C 
2.04 

0— N 
i-95 

F— 0 
3.10 

3 

Mg — Na 
0.94 

Al— Mg 
3.10 

Si— Al 
0.96 

P— Si 
2.96 

S— P 
1.02 

Cl— S 
3-39 

4 

Ca— K 
0.88 

Sc — Ca 
4.06 

Ti— Sc 
4-03 

V— Ti 
3-io 

Cr— V 
1-35 

Mn — -Cr 
2-35 

5 

Zn — Cu 
1.70 

Ga — Zn 
5.02 

— 

Se — As 
3-97 

Br— Se 
0.89 

6 

Sr— Rb 
2.10 

Y— Sr 
2.30 

Zr— Y 
0.80 

Nb— Zr 
3-30 

Mo— Nb 
2.20 

— 

7 

Cd-Ag 

4.04 

In— Cd 
1.70 

Sn — In 
3-95 

Sb — In 
2.25 

Te— Sb 
5-40 

I— Te 
i-54 

8 

Ba — Cs 
4. 16 

La — Ba 
1.64 

9 

:::: 

IO 

.... 

W— Ta 
1.60 

II 

Hg— Au 
3.60 

Tl-Hg 

3-90 

Pb— Tl 
2.69 

Bi— Pb 
1. 11 

— 

periods  as  those.  They  are  alternately  attracting  and 
repelling. 

He  thought  that  the  proximate  cause  for  a periodicity 
in  the  physical  properties  must  be  a corresponding 
periodicity  of  the  force  acting  between  the  atoms  : and 
that  periodically  variable  forces  acting  between  the  atoms 
are  generated  by  periodic  movements  of  the  latter,  by 
which  the  surrounding  ether  is  caused  to  vibrate.  The 
amplitudes  of  these  vibrations  are  governed  by  the 
energy  of  the  atomic  movements,  which  is  a periodic 


184 


THE  PERIODIC  LAW. 


function  of  the  atomic  weight,  and  in  their  turn  govern 
the  strength  of  the  generated  force. 

The  atomic  weight  differences  were  also  discussed  by 
him  and  brought  into  conformity  with  a periodic  law. 
(See  table.)  The  reasoning  used  throughout  the  work 
is  largely  mathematical. 

A certain  amount  of  periodicity  is  observable  in  this 
table.  There  are  imperfections  which  would  largely  ob- 
scure the  actual  degree  of  regularity  to  be  observed  in 
these  atomic  weight  differences.  The  table  needs  no 
detailed  explanation. 

129.  Relations  between  the  Atomic  Weight  Differences 
Observed  by  Rydberg. — In  the  second  paper  (152)  the 
starting  point  of  the  examination  was  the  observ ation  that 
the  majority  of  the  smaller  atomic  weights  are  nearly 
whole  numbers  though  they  do  not  absolutely  coincide 
with  them.  The  probability  that  this  is  no  accident  is 
found  sufficient  to  justify  writing  the  atomic  weights  in 
the  form  N-\-d  where  A^is  a whole  number.  The  dif- 
ferences in  the  value  of  N for  the  first  accurately  known 
atomic  weights  showed  on  examination  that  they,  with 
few  exceptions,  possess  the  value  \n  or  \n  -(-  3.  A closer 
examination  revealed  that  the  form  \n  -j-  3 belonged  to 
the  elements  of  odd  valence  and  4 n to  those  of  even. 
The  probability  that  this  was  accidental  was  found  to 
be  very  small. 

In  order  to  find  the  d values  two  suppositions  were 
made  : 

1.  That  the  forms  \n  + 3 and  4 n respective!}-  hold 
good  for  all  elements. 


REYNOLD’S  DIAGRAM. 


185 


2.  That  the  difference p of  the  lvalues  was  constant 
for  two  consecutive  elements  of  the  same  group.  Ac- 
cording to  (1),  p must  have  the  form  4 n. 

The  value  of  p was  found  constant  and  equal  to  44  by 
comparing  the  extreme  members  of  each  group.  By 
this  the  justice  of  the  supposition  was  placed  beyond 
doubt  and  the  values  for  iVand  d perfectly  determined. 
Lastly,  the  d values  of  the  two  series  of  elements  (odd 
and  even  valences)  were  examined  separately.  They 
proved  to  be  periodic  functions  of  N (or  n. ) The  length 
of  the  period  was  equal  to  44  ( 1 1 ) ; d—x — N where  x is  the 
observed  atomic  weight  and  N is  the  calculated  one. 
He  concluded  that  it  is  impossible  to  longer  regard  the 
elements  as  simple  independent  bodies. 

It  is  scarcely  necessary  to  poinf  out  the  very  doubtful 
character  of  the  d values.  Yet  the  author  attached 
much  importance  to  them.  He  thought  that  they  point 
to  the  atoms  being  made  up  of  hydrogen  atoms  and  a 
second  periodic  constituent  (H  may  possibly  be  divided 
itself) . This  member  he  said  might  enclose  the  kernel  of 
hydrogen  atoms  as  an  envelope.  He  noted  the  close  con- 
nection between  the  curve  gotten  for  these  values  and 
the  curves  for  the  physical  properties  of  the  elements. 
Tables  are  given  in  the  original  papers  containing  these 
curves. 

130.  Reynold’s  Diagram  Representing  the  Periodic 
Law. — In  1886  Reynolds  devised  a diagrammatic  re- 
presentation of  the  periodic  law  (155)  which  has  been 
often  made  use  of  since  by  lecturers  upon  the  subject. 
The  diagram  is  very  similar  to  the  one  used  five  years 


THE  PERIODIC  LAW. 


1 86 

previously,  by  Spring  (p.  178)  for  his  classes  but  not 
brought  to  the  notice  of  the  general  chemical  public. 

Reynolds  seized  upon  what  he  regarded  as  the  most 
salient  features  of  the  periodic  law  for  representation. 

1.  The  transition^r  saltum  from  one  seven  to  another 
e.  g. , chlorine  to  potassium  etc., 

2.  The  fourth  element  in  each  series,  in  general,  pos- 
sesses properties  which  a transition  member  might  be 
expected  to  possess.  Thus  silicon  might  be  represented 
as  the  apex  of  a tolerably  symmetrical  curve  which  should 
represent  for  the  particular  period  the  direction  in  which 
the  properties  of  the  series  of  elements  vary  with  rising 
atomic  weight.  A physical  analogy  will  help  to  make 
the  meaning  of  this  clear.  See  Fig.  1. 

Let  the  line  A B represent  part  of  a string  in  tension, 
and  #,  b,  c,  d,  e,f,  g,  seven  knots  upon  it.  The  string 
is  now  thrown  into  a number  of  vibrating  segments  : 
0 and  o'  represent  two  nodal  points  between  which  one 
segmental  vibration  takes  place.  The  several  knots  oscil- 
late rapidly  to  and  fro  in  the  direction  of  the  dotted  lines,  a 
moving  from  the  position  of  rest  to  a and  back  again, 
when  it  swings  to  the  same  extent  on  the  opposite  side 
of  the  line  AB,  returns  and  starts  afresh.  Each  knot 
performs  similar  journeys,  but  the  lengths  of  the  paths 
vary  : then  the  length  increases  from  a to  b,  from  b to  c 
and  from  c to  d,  while  it  diminishes  from  d to  e,  e to / , 
and  f to  g . The  knot  d is  therefore  exceptional,  in  that 
it  suffers  the  maximum  displacement  from  the  mean  posi- 
tion : the  knots  c and  e perform  journeys  of  comparable 
length  but  they  are  otherwise  in  more  or  less  direct  cun- 


B 


Fig.  i. 


i88 


THE  PERIODIC  DAW. 


trast  : similarly  b and  /,  a and  g,  form  contrasted 
pairs. 

Let  the  knots  in  the  string  represent  the  atomic  group- 
ings we  call  elements  arranged  in  the  order  of  atomic 
weight  (not  necessarily  symmetrical,  as  in  the  case  of 
the  knotted  string)  rising  from  a to  g and  we  have  a 
picture  of  a period  of  seven  elements  regarded  as  a vibra- 
ting system.  The  elements  corresponding  to  d at  its 
maximum  displacement  he  called  meso-elements.  He 
noted,  in  examining  the  periods  : 

1.  That  the  three  elements  of  lower  atomic  weight 
than  the  meso-elements  are  electro-positive  in  character 
while  those  of  higher  atomic  weight  are  electro-negative. 

2.  That  the  numbers  above  and  below  the  meso-ele- 
ments  fall  into  pairs  of  elements  which,  while  exhibiting 
certain  analogies,  are  generally  in  more  or  less  direct 
chemical  contrast. 

He  noted,  further,  that  valence  alone  is  an  untrust- 
worthy guide  to  the  probable  position  of  an  element  in 
a period. 

“ The  pairs  of  more  or  less  contrasted  elements  may 
be  likened  to  the  pairs  of  knots  on  the  string  whose 
paths  of  vibration  are  of  approximately  equal  length  ; 
but  it  is  convenient  for  the  purpose  of  graphic  illustration 
to  assume  that  the  paths  of  each  pair  are  of  the  same 
length  or  that  the  displacements  are  in  the  ratios  of  i : 
2:3:  4, — that  of  d,  Fig.  1 , which  is  the  longest.  On  re- 
ference to  the  diagram,  Fig.  1,  the  nature  of  this  arrange- 
ment will  be  evident,  and  the  portions  when  connected 
as  shown  are  seen  to  form  an  expanding  curve  such  as 


REYNOLD’S  DIAGRAM.  189 

would  be  afforded  by  a string  or  chain  whose  parts  are 
in  unequal  tension.1 

“With  the  aid  of  the  scale  AB  there  is  no  difficulty  in 
picturing  the  elements  in  the  position  of  the  knots  on 
the  string,  and  so  regarding  them  as  members  of  a vibra- 
ting system.  All  the  elements  w’hose  constants  are 
well-known  find  places  on  the  curve.  Thus  the  physical 
analogy  helps  us  to  form  some  conception  of  the  relations 
of  the  members  of  the  periods  and  of  the  latter  to  one 
another.  Moreover  the  admission  of  the  periodic  princi- 
ple at  all  seems  to  require  the  recognition  of  similar  re- 
lations to  those  indicated. 

He  mentioned  as  points  brought  out  by  the  scheme  : 

1.  The  transition  per  saltum  disappears  as  a difficulty. 

2.  Hydrogen  is  in  the  Mendeleeff  table  the  first  mem- 
ber of  a period  of  seven,  the  remaining  six  being  un- 
known. If  the  form  of  the  curve  is  allowed  to  influence 
the  judgment  the  position  of  hydrogen  in  reference  to 
that  of  lithium  is  rather  that  of  the  last  member  of  one 
period  to  the  first  of  another. 

3.  The  odd  and  even  periods  of  Mendeleef  are  at  once 
distinguished. 

4.  The  general  contour  of  the  curve  is  such  that  we 
are  not  permitted  to  assume  the  existence  of  Mendeleeff’s 
ninth  period.  Six  out  of  the  seven  elements  tabulated 
by  Mendeleeff  are  unknown. 

l Prof.  Fitzgerald  suggested  that  a vibrating  metallic  chain,  suspended 
from  the  ceiling  and  attached  to  the  floor,  would  afford  a more  complete 
picture,  as  the  regular  and  considerable  changes  of  tension,  due  to  the  in- 
creasing weight,  would  lead  to  the  production  of  regular  expanding  loops. 


THE  PERIODIC  LAW. 


I90 

5.  The  elements  which  form  Mendeleeff’s  eighth  group 
are  found  near  to  three  of  the  ten  nodal  points.  These 
bodies  are  obviously  interperiodic,  in  the  sense  that 
their  atomic  weights  all  exclude  them  from  the  periods 
into  which  the  other  elements  fall  while  their  chemical 
relations  with  certain  members  of  the  adjacent  periods 
lead  to  the  conclusion  that  they  are  interperiodic  in  the 
special  sense  of  being  transitional  as  well. 

Notwithstanding  the  exclusion  of  Mendeleeff’s  ninth 
period  the  diagram  shows  that  a considerable  number  of 
elements  are  still  required  to  complete  the  system,  in 
the  opinion  of  the  author. 

131.  Crookes’  flodification  of  this  Diagram. — Crookes, 
(156)  in  a lecture  before  the  British  Association,  repro- 
duced this  diagram  of  Reynolds,  with  certain  modifica- 
tions which  may  be  seen  in  the  accompanjfing  figure. 
He  explained  at  some  length,  the  coincidences  and  other 
features  of  the  diagram. 

As  to  the  gaps  in  Mendeleeff’s  table,  he  said:  “ I do 
not,  however,  wish  to  infer  that  the  gaps  in  Mendeleeff’s 
table,  and  in  this  graphic  representation  of  it,  neces- 
sarily mean  that  there  are  elements  actually  existing  to 
fill  up  these  gaps  ; these  gaps  may  only  mean  that  at 
the  birth  of  the  elements  there  was  an  eas\r  potentiality 
of  the  formation  of  an  element  which  would  fit  into  the 
place.” 

He  further  said  that  the  symmetry  of  nearly  all  this 
series  proclaims  at  once  that  we  are  working  in  the  right 
direction.  The  anomalies  are  explained  as  springing 
from  imperfect  knowledge  of  the  elements  and  their 


CROOKES’  DIAGRAM. 


I9I 


atomic  weights.  He  added:  “The  more  I study  the 
arrangement  of  this  zig-zag  curve,  the  more  I am  con- 

O ? 


3 

-t 

1 


vinced  that  he  who  grasps  the  key  will  be  permitted  to 
unlock  some  of  the  deepest  mysteries  of  creation.  L,et 


7ctr*t®m'C\ 


192 


THE  PERIODIC  LAW. 


us  imagine  if  it  is  possible  to  get  a glimpse  of  a few  of 
the  secrets  here  hidden.  Let  us  picture  the  very  begin- 
nings of  time,  before  geological  ages,  before  the  earth 
was  thrown  off  from  the  central  nucleus  of  molten  fluid, 
before  even  the  sun  himself  had  consolidated  from  the 
original  protyle.  Let  us  still  imagine  that  at  the  primal 
stage  all  was  in  an  ultra-gaseous  state,  at  a temperature 
inconceivably  hotter  (the  author  says  he  is  constrained 
to  use  such  terms  as  temperature,  radiation,  and  cooling 
but  does  not  like  the  idea  of  the  periodic  motions  thus 
required  of  the  protyle)  than  anything  now  existing  in 
the  visible  universe  ; so  high,  indeed,  that  the  chemical 
atoms  could  not  yet  have  been  formed,  being  still  far 
above  their  dissociation  point.  In  so  far  as  protyde  is 
capable  of  radiating  or  reflecting  light,  this  vast  sea  of 
incandescent  mist,  to  an  astronomer  in  a distant  star, 
might  have  appeared  as  a nebula,  showing  in  the  spec- 
troscope a few  isolated  lines,  fore-casts  of  hydrogen, 
carbon  and  nitrogen  spectra. 

“But  in  course  of  time  some  process  akin  to  cooling, 
probably  internal,  reduces  the  temperature  of  the  cosmic 
protyle  to  a point  at  which  the  first  step  in  granulation 
takes  place  : matter  as  we  know  it  comes  into  existence, 
and  atoms  are  formed.  As  soon  as  an  atom  is  formed 
out  of  protyle  it  is  a store  of  energy,  potential  (from  its 
tendency  to  coalesce  with  other  atoms  by  gravitation  or 
chemically)  and  kinetic  (from  its  eternal  motion. ) To 
obtain  this  energy  the  neighboring  protyle  must  be  re- 
frigerated by  it  and  thereby  the  subsequent  formation  of 
other  atoms  will  be  accelerated.  But  with  the  birth  of 


CROOKES’  DIAGRAM. 


193 


atomic  matter  the  various  forms  of  energy,  which  require 
matter  to  render  them  evident,  begin  to  act;  and  amongst 
others,  that  form  of  energy  which  has  for  one  of  its  factors 
what  we  call  atomic  weight.  Let  us  assume  that  the  ele- 
mentary protyle  contains  within  itself  the  potentiality  of 
every  possible  combining  proportion  or  atomic  weight. 
Let  it  be  granted  that  the  whole  of  our  known  elements 
were  not  at  this  epoch  simultaneously  created.  The 
easiest  formed  element,  the  one  most  nearly  allied  to  the 
protyle  in  simplicity,  is  first  born.  Hydrogen,  or  shall 
we  say  helium,  of  all  the  known  elements  the  one  of 
simplest  structure  and  lowest  atomic  weight,  is  the  first 
to  come  into  being.  For  some  time  hydrogen  would  be 
the  only  form  of  matter  (as  we  know  it)  in  existence, 
and  between  hydrogen  and  the  next  formed  element  there 
would  be  a considerable  gap  in  time,  during  the  latter 
part  of  which  the  element  next  in  order  of  simplicity 
would  be  slowly  approaching  its  birth-point : pending 
this  period  we  may  suppose  that  the  evolutionary  pro- 
cess which  soon  was  to  determine  the  birth  of  a new  ele- 
ment, would  also  determine  its  atomic  weight,  its  affini- 
ties, and  its  chemical  position. 

“In  this  way  it  is  conceivable  that  the  succession  of 
events  which  gave  us  such  groups  as  Pt,  Os,  and  Ir  ; Pd, 
Ru,  and  Rh  ; Fe,  Ni,  and  Co,  if  the  operation  of  genesis 
had  been  more  greatly  prolonged,  would  have  resulted 
in  the  birth  of  only  one  element  in  the  place  of  these 
groups.  It  is  also  probable  that  by  a much  more  rapid 
rate  of  cooling,  elements  would  originate  even  more 
closely  related  than  are  Ni  and  Co,  and  thus  we  should 


194 


THE  PERIODIC  LAW. 


have  formed  the  nearly  allied  elements  of  the  cerium, 
yttrium  and  similar  groups  ; in  fact,  the  minerals  of  the 
class  of  samarskite  and  gadolinite  may  be  regarded  as 
the  cosmical  lumber-room  where  the  elements  in  a state 
of  arrested  development,  the  unconnected  missing  links 
of  inorganic  Darwinism,  are  finally  aggregated. 

“I  have  said  that  the  original  protyle  contained  within 
itself  the  potentiality  of  all  possible  atomic  weights.  It 
may  well  be  questioned  whether  there  is  an  absolute 
uniformity  in  the  mass  of  every  ultimate  atom  of  the 
same  chemical  element.  Probably  our  atomic  weights 
merely  represent  a mean  value  around  which  the  actual 
atomic  weights  of  the  atoms  vary  within  certain  narrow 
limits. 

“Each  well-defined  element  represents  a platform  of 
stability  connected  by  ladders  of  unstable  bodies.  In 
the  first  accreting  together  of  the  primitive  stuff  the 
smallest  atoms  would  form,  then  these  would  join  to- 
gether to  form  larger  groups,  the  gulf  across  from  one 
stage  to  another  would  be  gradually  bridged  over,  and 
the  stable  element  appropriate  to  that  stage  would  absorb, 
as  it  were,  the  unstable  rungs  of  the  ladder  which  lead 
up  to  it.  I conceive  therefore  that  when  we  say  the 
atomic  weight  of,  for  instance,  calcium  is  40,  we  really 
express  the  fact  that  while  the  majority  of  the  calcium 
atoms  have  an  actual  atomic  weight  of  40,  there  are  not 
a few  which  are  represented  by  39  or  41,  a less  number 
by  38  or  42,  and  so  on.  We  are  here  reminded  of  New- 
ton’s “old  worn”  particles. 

“ Is  it  not  possible,  even  feasible,  that  these  heavier  or 


CROOKES’  DIAGRAM. 


J95 


lighter  atoms  may  have  been  in  some  cases  subsequently 
sorted  out  by  a process  resembling  chemical  fractiona- 
tion? This  sorting  out  may  have  taken  place  in  part 
while  atomic  matter  was  condensing  from  the  primal 
state  of  intense  ignition,  but  it  also  may  have  been  partly 
effected  in  geological  ages  by  successive  solution  and  re- 
precipitations of  the  various  earths.” 

The  author  then  reported  some  of  his  own  work  upon 
the  fractionation  of  the  earths  present  in  samarskite  and 
gadolinite  and  the  spectroscopic  work  done  upon  them 
as  ‘‘apposite  to  this  question.”  The  theory  is  then 
pressed  a step  or  two  further  to  elucidate  the  matter  of 
elemental  evolution  and  the  diagram  is  again  called  into 
use. 

In  the  undulating  curve  of  the  diagram  he  recognized 
two  forces,  one  acting  in  the  direction  of  the  vertical  line 
and  the  other  pulling  backwards  and  forwards  like  a pen- 
dulum. The  vertical  line  may  represent  temperature, 
sinking  from  the  dissociation  point  of  the  first  formed  ele- 
ment to  that  of  the  last.  The  oscillating  line  must  be  inti- 
mately connected  with  electricity  from  the  peculiar  prop- 
erties, atomicity,  electro-positive  and  electro-negative 
characters  which  it  confers.  He  further  assumes  that 
it  is  identical  with  chemical  energy. 

‘‘The  elements  formed  would  not  all  have  the  same 
stability,  some  would  be  unable  to  endure  the  slightest 
disturbance  of  the  unstable  equilibrium  in  which  they 
took  their  rise  ; others  would  endure  longer  but  would 
ultimately  break  down  as  temperature  and  pressure 
varied.” 


1 96 


THE  PERIODIC  LAW. 


He  incorporated  in  the  diagram  the  observation  of 
Carnelley  that  the  elements  in  the  even  series  of  Mende- 
leeff  are  paramagnetic  and  those  in  the  odd  series  are 
diamagnetic  but  acknowledged  that  there  are  exceptions, 
as  indeed  can  be  seen  in  his  diagram,  and  that  our 
knowledge  on  this  point  is  imperfect. 

When  the  temperature  on  the  vertical  line  sinks  below 
the  dissociation  point  of  uranium,  the  author  thought  it 
possible  that  the  elements  began  to  unite  and  compounds 
were  formed . At  a temperature  higher  tnan  the  dissocia- 
tion point  of  hydrogen  he  mentioned  the  possibility  of  the 
existence  of  elements  of  negative  atomic  weight  as  called 
for  by  Carnelley.  He  quoted  from  Helmholtz  (Faraday 
Lecture  1881.)  “If  we  accept  the  hypothesis  that  the 
elementary  substances  are  composed  of  atoms,  we  can- 
not avoid  concluding  that  electricity  also,  positive  as 
well  as  negative,  is  divided  into  definite  elementary 
portions,  which  behave  like  atoms  of  electricity’’  and  he 
suggested  electricity  as  one  of  the  negative  elements  and 
luminiferous  ether  as  another. 

This  genesis  of  matter  was  then  extended  to  the  whole 
cosmic  system.  Dr.  Crookes  was  careful  to  point  out  that 
there  is  no  direct  proof  of  such  a genesis  of  the  elements 
and  called  it  a “provisional  hypothesis.” 

132.  Crookes’  Genesis  of  the  Elements. — A few  months 
later  ( 1 63)  Crookes  followed  up  this  same  subject  in  a lec- 
ture delivered  before  the  Royal  Institution  upon  the  ‘ ‘ Gen- 
esis of  the  Elements.”  In  this  he  examined  first  into  the 
occurrence  of  the  elements.  Bodies  are  found  grouped 
together  in  definite  proportions  with  other  bodies  from 


CROOKES’  GENESIS  OF  THE  ELEMENTS. 


197 


which  they  differ  exceedingly  and  to  which  they  are 
held  by  affinity  more  or  less  strong.  To  separate  them 
that  affinity  must  be  overcome.  The  combined  bodies 
usually  differ  very  widely  in  their  atomic  weights. 

Again  bodies  are  found  associated  with  others  closely 
allied  to  themselves.  They  are  not  held  together  by  any 
decided  affinity  nor  in  definite  proportions  and  their 
atomic  weights  are  often  almost  identical.  They  show 
similar  behavior  towards  chemical  reagents  and  this 
renders  their  separation  difficult.  The  most  striking  in- 
stance of  such  occurrence  is  found  in  the  case  of  the  so- 
called  rare  earths. 

The  method  of  separating  these  by  fractionation  was 
given  in  outline  and  then  the  method  of  examining,  by 
means  of  the  spectroscope,  the  light  given  off  by  these 
purified  simple  bodies  under  the  action  of  induction 
sparks  in  a high  vacuum.  The  complicated  and  puzz- 
ling nature  of  these  spectra  was  mentioned.  The  spectrum 
given  by  an  element  was  regarded  as  an  unalterable  index 
of  that  element.  If  yttrium,  one  of  the  rare  earths,  be 
fractioned  by  prolonged  and  careful  work  it  is  separated 
into  the  extremes  which  differ  chemically  from  yttrium 
and  more  markedly  from  one  another,  yet  all  give  the 
same  spectrum. 

As  an  explanation  the  following  view  is  offered.  Be- 
tween the  molecules  wre  are  accustomed  to  deal  with  in 
chemical  reactions  and  the  ultimate  atoms  as  first  created, 
come  smaller  molecules  or  aggregates  of  physical  atoms  : 
these  sub-molecules  differ  one  from  another,  according 
to  the  position  they  occupied  in  the  edifice.  To  illustrate, 


THE  PERIODIC  LAW. 


198 

the  yttrium  may  be  represented  by  a five  shilling  piece. 
By  chemical  fractionation  it  is  divided  into  five  separate 
shillings.  These  are  seen  to  be  not  counterparts  but, 
like  the  carbon  atoms  in  the  benzene  ring,  have  the  im- 
press of  their  positon  1,  2,  3,  4,  5,  stamped  upon  them. 
If  these  shillings  are  examined  by  a more  powerful  agent, 
e.  g .,  thrown  into  the  melting  pot,  they  all  turn  out  to  be 
silver.  So  the  yttrium  and  its  fractions  all  under  the 
electric  spark  give  the  same  spectra  though  they  give 
different  phosphorescent  spectra.  Another  hypothesis 
is  that  here  are  new  chemical  elements  differing  so 
slightly  in  properties  as  to  admit  of  only  imperfect  separa- 
tion. Then  it  is  shown  that  the  original  spectrum  can 
be  reproduced  by  using  appropriate  mixtures  and  hence 
that  it  may  be  caused  by  a constant  mixture  and  is  not 
necessarily  indicative  of  a single  element.  Crookes 
made  mention  of  the  fact  that  Lecoq  de  Boisbaudran 
refers  the  phosphorescent  spectra  to  impurities  in  the 
preparation. 

He  also  referred  to  the  remarkable  discovery  of  Norden- 
skiold1  who  had  been  working  along  the  same  line  as 
himself.  This  was  that  the  oxide  of  gadolinium,  though  it 
is  not  the  oxide  of  a simple  body,  but  a mixture  of  three 
isomorphous  oxides,  even  when  it  is  derived  from  totally 
different  minerals  found  in  localities  far  apart  from  one 
another,  possesses  a constant  atomic  weight.  This  is  a 
new  fact  in  chemistry  that  three  isomorphous  substances 
derived  from  different  elements  occur  in  nature  not  only 
always  together  but  always  in  the  same  proportions. 

iComp.  Rend.,  Nov.  2,  1886. 


GRAVITATION  AND  THE  ATOMIC  WEIGHTS.  199 

“What  is  true  of  yttrium  and  of  gadolinium  may  be  as- 
sumed as  true  of  all  elements.  In  some  (possibly  in  all) 
the  whole  spectrum  does  not  emanate  from  all  their  atoms 
but  different  spectral  rays  may  come  from  different  atoms 
and  in  the  spectrum,  as  we  see  it,  all  these  partial  spectra 
are  present  together.  This  may  be  interpreted  to  mean 
that  there  are  definite  differences  in  the  internal  motions 
of  the  several  groups  of  which  the  atoms  of  a chemical 
element  consist.  Another  important  inference  is  that 
yttrium  atoms,  though  differing,  do  not  differ  contin- 
uously but  per  saltum .” 

The  discovery  of  the  composite  nature  of  didymium 
by  Welsbach  was  alluded  to.  “If  we  onty  had  the  right 
methods,  why  could  not  calcium  and  others  be  decom- 
posed.” He  “ventures  provisionally  to  conclude  that 
the  so-called  elements,  or  simple  bodies,  are  in  reality, 
compound  molecules.”  The  author  then  by  means  of  the 
primal  element  protyle  and  the  force  electricity  constructed 
the  various  elements,  using  the  Reynolds  diagram  as  de- 
scribed in  the  preceding  section,  the  latter  portion  of  this 
lecture  being  a repetition  of  the  one  before  the  British 
Association. 

i33.  Dulk  upon  Gravitation  and  the  Atomic  Weights. 

— Gravitation  is  so  far  as  known  a property  of  the  atoms, 
said  the  author,  (157 , 158)  and  furthermore  the  only 
property  which  in  its  influence  upon  the  atom,  as  shown 
in  the  atomic  weight,  furnishes  the  one  unchangeable 
characteristic  of  the  atom.  “This  being  the  one  unchang- 
ing property  of  the  atoms  there  have  been  many  attempts 
at  solving  the  relations  existing  between  them.  It  is 


200 


THE  PERIODIC  LAW. 


necessary  now  to  form  an  hypothesis  which  will  give  the 
relations  of  the  atoms  to  gravitation.”  The  effort  to  do 
this  is  based  upon  the  alkali  metals.  It  is  presupposed 
that  the  atoms  do  not  consist  of  different  quantities  of 
matter  of  the  same  kind  but  that  each  atom,  differing 
chemically,  consists  of  a peculiar  matter,  a condensation 
of  the  cosmic  ether.  If  the  atoms  are  represented  as 
circles  then  certain  ratios  can  be  detected  between  the 
squares  of  the  radii  of  two  or  more  of  the  circles  which 
correspond  with  the  differences  of  successive  members 
of  the  same  family  or  corresponding  members  of  different 
families.  The  ratios  of  the  atomic  weights  can  be  re- 
presented by  geometrical  figures,  for  which  reference 
must  be  made  to  the  original  articles. 

134.  Phipson’s  Outlines  of  a New  Atomic  Theory. — In 

a singular  pamphlet,  the  author  stated  (159)  : ‘‘The  old 
notion  that  matter  is  composed  of  atoms  and  spaces  is 
doubtless  correct  and  it  can  be  argued  successfully  that 
atomsare  extremely  minute  spheres.  The  space  between 
the  atoms  is  filled  with  phlogiston.” 

The  law  of  volumes  is  reversed  by  the  author  after 
this  fashion  : “ Equal  gaseous  volumes  contain  a differ- 
ent number  of  atoms  all  of  the  same  size  and  same 
weight.  This  implies  that  the  atoms  are  all  of  the  same 
nature  and  proclaims  the  unity  of  matter.  Whatever 
substance  may  be  under  consideration  its  atoms  are  all 
of  the  same  nature,  and  they  are  separated  by  space, 
which  we  call  phlogiston,  a term  that  implies  movement, 
light,  heat,  electricity,  etc.  The  greater  the  amount  of 


valence  and  atomic  weight. 


201 


phlogiston  the  greater  the  energy  of  the  system  of  atoms 
termed  an  element.” 

The  matter  of  all  the  elements  is  therefore  identical  ; 
the  phlogiston  alone  varies,  that  is,  the  space  between 
the  atoms  (considered  at  rest)  or  their  extent  of  motion. 
A chemical  element  is  therefore  a system  of  atoms,  the 
properties  of  which  depend  upon  its  phlogiston  and  the 
amount  of  the  latter  is  deduced  from  the  weights  which 
combine  together.” 

The  author  then  offered  explanations  of  various  phe- 
nomena, allotropism,  galvanic  couples,  etc.  No  ex- 
perimental nor  other  proof  is  offered  for  his  theory. 

•35-  Reed’s  Graphical  Representation  of  the  Relation 
between  Valence  and  Atomic  Weight.  — Reed  (164) 
started  with  three  hypotheses  which  were  first  announced 
though  in  a different  manner,  by  Johnson. 

1.  The  valence  of  an  atom  is  its  capacity  for  electro- 
polarity. 

2.  The  polarity  of  an  integrant  molecule  is  always  zero. 

3 . Positive  and  negative  changes  of  polarity  are  always 
cotemporaneous  and  equal. 

All  the  atoms  in  a molecule  are  to  be  considered  as 
polarized,  one  half  the  atoms  (measured  in  valence  not 
in  numbers)  positively  and  the  other  half  negatively;  an 
atom  is  neutralized  when  it  is  united  with  one  or  more  atoms 
having  the  same  degree  of  polarity  but  of  opposite  sign, 
neutralization  meaning  opposition  and  not  that  the 
polarity  is  destroyed.  The  atomic  weights  and  observed 
valence  of  the  elements  are  given  and  the  principal  com- 
pounds in  which  those  valences  occur.  In  compounds 


202 


THE  PERIODIC  UW. 


which  can  not  be  electrolyzed,  the  more  basic  elements 
are  considered  electro-positive  and  the  more  acid  electro- 
negative. 

The  diagram  is  plotted  as  follows  : Two  straight  lines 
meet  at  right  angles  at  zero,  the  vertical  line  represent- 
ing valence  multiplied  by  ten  and  extending  to  40  below 
zero,  and  the  horizontal  line  representing  the  atomic 
weights  ; a point  is  located  on  the  plane  for  the  maximum, 
minimum  and  characteristic  valence  of  each  element,  and 
nearly  all  these  points  are  found  to  lie  on  a double  series 
of  parallel  lines,  the  successive  pairs  of  which  are 
separated  by  equal  distances.  The  deviations  from  these 
positions  is  so  slight  as  to  be  barely  noticeable  on  the 
scale  used. 

It  was  found  that  the  loci  of  two  equations,  y=a 
(x — 4)  and  y = a (x  — 5),  pass  through  or  near  the 
points  corresponding  to  more  than  fifty  of  the  ele- 
ments whose  physical  characteristics  are  most  accu- 
rately known  ; provided  the  plane  is  wrapped  around 
a cylinder  having  its  axis  parallel  with  the  axis 

of  abscissae  and  its  radius  R = — . The  loci  of 

n 

these  equations  now  become  parallel  helices,  that  cut 
the  axis  of  abscissae  at  intervals  of  sixteen  units  of  atomic 
weight.  The  ordinates  become  arcs  of  circles  formed  b}^ 
planes  cutting  the  cylinder  at  right  angles  to  its  axis. 
The  axis  of  abscissae  becomes  an  element  of  the  surface 
of  the  cylinder.  The  circumference  of  the  cylinder 
measures  eight  units  of  valence.  Valence  is  measured 
upward  from  the  axis  of  abscissae,  if  it  is  positive,  and 


gruenwald’s  spectrum  analysis.  203 

downwards,  if  it  is  negative.  The  full  development  of 
this  system  requires  an  entire  group  of  hitherto  undis- 
covered elements  to  which  peculiar  properties  are 
ascribed.  The  number  is  fifteen  and  the  valence 
would  be  either  eight  or  zero  ; they  would  be  volatile 
and  non-atomic,  etc.  The  arrangement  resembles  that 
of  Gibbes,  in  some  respects,  more  closely  than  that  of 
de  Chancourtois.  The  idea  of  the  helix  is,  of  course, 
an  old  one.  In  this  instance  it  is  more  thoroughly  worked 
out  than  in  previous  attempts. 

After  considering  the  diagram  and  pointing  out  some 
periodic  and  recurrent  combinations,  Reed  concluded 
that,  “saturation  valence  is  an  equi-crescentrotatory 
function  of  the  atomic  weight”  and  in  order  to  represent 
this  idea  graphically  he  located  the  points  on  the  surface  of 
a cylinder  instead  of  on  a plane.  He  next  pointed  out 
that  he  had  considerable  grounds  on  which  to  base  the 
conclusion  just  quoted,  which  he  claimed  could  hardly 
be  a coincidence  from  the  fact  that  it  united  not  less  than 
fifty  of  the  chemical  elements  by  so  simple  a relation  be- 
tween valence  and  atomic  weight.  Whether  this  con- 
clusion was  or  was  not  the  expression  of  a natural  law 
he  left  for  others  to  decide  after  mature  consideration. 

136.  Gruenwald’s  Mathematical  Spectrum  Analysis. 
— During  the  years  1887  and  1888,  Griinwald  published 
three  papers  (165)  in  the  Astronomische  Nachrichten 
and  the  Monatshefte fur  Chemie  upon  the  mathematical 
relations  or  coincidences  of  the  spectra  of  water  vapor, 
oxygen,  hydrogen,  magnesium,  cadmium  and  carbon. 
The  object  of  these  investigations  was  to  discover 


204 


THE  PERIODIC  LAW. 


relations  between  the  elements  by  means  of  the 
spectra,  and,  if  possible,  in  this  way  to  reduce  them 
to  their  simpler  components  or  fundamental  elements. 
His  method  of  work  was  to  compare  the  groups  of  lines 
in  any  two  chemical  elements  under  consideration.  He 
concluded  that  they  have  a common  component  if  a 
group  of  lines  in  one  when  multiplied  by  a simpler  num- 
ber gave  the  lines  of  a group  in  the  spectrum  of  the  other 
element.  This  numerical  factor  was  thought  to  give  the 
ratio  of  the  volumes  occupied  by  the  common  constituent 
in  unit  volumes  of  the  two  substances. 

In  this  way  formulas  can  be  calculated  for  the  different 
elements.  Thus  in  the  spectrum  of  hydrogen  there  are 
two  groups  of  lines  a and  b which  multiplied  by  and 
f give  corresponding  groups  in  the  spectrum  of  water, 
and,  since  hydrogen  has  ■§  of  the  volume  of  water  the 
equations  are  gotten  ; a-\-  b = i ; a -|-  f £ = f ; a = f ; 
b—\  and  the  formula  for  hydrogen  is  ba 4.  Griinwald 
called  the  substance  a,  coronium,  and  b,  helium.  For 
oxygen  he  gave  the  formula  JTb 4 (btc)  where  c is  a new 
substance,  though  he  afterwards  considered  c merely  a 
in  a different  state  of  compression. 

Adopting  the  water  spectrum  as  a standard  he  gave 
various  means  of  recognizing  the  presence  of  these 
primary  elements  a and  b in  the  various  spectra.  These 
criteria  he  applied  to  the  spectra  of  carbon,  magnesium, 
and  cadmium  and  found  them  made  up  of  the  two  ele- 
ments a and  b in  different  states  of  compression.  Griin- 
wald used  various  factors  for  the  transformation  of  these 
groups  of  lines.  The  groups  of  lines  of  the  shortest 


CRITICISM  OF  GRUENWALD. 


205 


wave-lengths  are  connected  with  the  substance  b and  the 
greater  wave  lengths  with  a.  An  examination  of  a num- 
ber of  the  elements  convinced  him  that  “ many,  perhaps 
all,  bodies  hitherto  considered  as  elements  were  com- 
pounds, composed  of  condensation  forms  of  the  primary 
elements  a and  b,  of  hydrogen  = bat,  in  various  physical 
modifications.”  This  theory  he  supported  by  a great 
array  of  confirmatory  measurements  and,  as  has  been 
said, he  connected  these  two  substances  with  the  remarka- 
ble color  spectrum  line  helium  and  the  well-marked  line 
of  the  sun’s  corona,  coronium,  regarding  both  as  con- 
stituents of  hydrogen  gas. 

137.  Ames’  Criticism  of  Gruenwald. — This  work  of 
Griinwald  attracted  a good  deal  of  attention.  The  con- 
clusions were  regarded  as  highly  probable  by  Liveing 
and  Dewar  but  met  with  strong  criticism  from  an  American 
source.  This  was  Joseph  S.  Ames  of  the  Johns  Hopkins 
Physical  Laboratory  (185).  His  criticism  was  as  fol- 
lows : ‘ 1 There  are  two  distinct  questions  to  be  answered : 
(1)  Are  there  any  numerical  relations  connecting  the 
spectra  ofthe  elements  ? and  if  so,  (2)  What  is  the  mean- 
ing of  the  fact  ? Cornu,  Deslandres  and  others  have  long 
since  answered  the  first  question  for  us,  but  whether  Dr. 
Griinwald’s  answer  to  the  second  one  is  correct  or  not 
depends  upon  the  completeness  with  which  the  numerical 
relations  hold  for  the  entire  spectra  of  the  substance. 
It  is  here  that  Dr.  Griinwald’s  work  can  be  criticized. 

“ As  noted,  the  spectrum  of  the  oxy-hydrogen  flame 
is  used  to  test  the  existence  of  lines  belonging  to  a and  b. 
By  far  the  most  accurate  and  complete  determination  of 


206 


THE  PERIODIC  LAW. 


this  spectrum  is  that  of  Diveing  and  Dewar1  but  this 
does  not  always  answer  Dr.  Griinwald’s  purposes.  In 
the  British  Association  Report  for  1886  there  is  a pro- 
visional list  of  lines  of  the  water  spectrum  which  he 
often  uses,  although  the  wave-lengths  have  since  been 
corrected.  Further  if  other  lines  are  necessary,  they  are 
found  by  halving  the  wave-lengths  of  the  secondary 
spectrum  of  hydrogen.  Many  lines  thus  determined  are 
actually  present  in  the  water-spectrum  but  why  are  they 
not  all  there?  Dr.  Griinwald  says  it  is  because  the 
amplitude  of  vibration  of  parts  of  the  molecule  can  be  so 
changed,  owing  to  the  presence  of  other  substances, 
that  the  intensity  may  increase  or  diminish  or  become 
too  faint  to  be  observed.  To  this  argument  there  is 
absolutely  no  answer.  In  some  cases,  too,  the  average 
of  two  wave-lengths  is  used  as  a criterion  of  a w7ave  length 
of  b which  falls  between  them.  And  as  a last  resort,  if 
the  necessary  wave  length  can  not  be  found  in  the  w?ater 
spectrum  by  any  of  these  means,  it  is  put  down  as  ‘ ‘ new’  ’ 
and  is  called  an  “ unobserved”  line.  As  just  shown, 
Dr.  Griinwald  easily  explains  why  the  strongest  lines  in 
the  spectrum  of  an  element,  cadmium  for  example,  when 
‘‘  transformed”  into  wrater  lines,  may  be  faint  ; and 
vice  versa.  But  how  does  he  account  for  the  fact  that 
double  lines  are  not  transformed  into  double  lines  ? This 
seems  to  me  a fundamental  objection.  The  concave- 
grating gives  the  only  accurate  method  of  determining 
the  ultra-violet  wave  lengths  of  the  elements  ; and  as  a 
consequence  of  not  using  it,  most  of  the  tables  of  wave- 

1 Phil.  Trans 1888. 


CRITICISM  OF  GRUENWALD. 


207 


lengths  so  far  published  are  not  of  much  value.  So 
Griinwald’s  error  may  be  great.  And,  besides  when  we 
consider  that  in  the  water-spectrum  as  given  by  Liveing 
and  Dewar,  without  the  help  of  the  secondary  spectrum 
of  hydrogen,  there  is  on  the  average  one  line  for  every 
two  Aengstrom  units,  it  would  be  remarkable  indeed  if 
any  law  could  not  be  verified.  This  is  strikingly 
shown  in  the  first  group  of  the  cadmium  lines.  Here 
6742  and  6740  are  two  readings  for  the  wave  lengths  of 
the  same  line,  as  made  by  two  observers  : yet  Griinwald 
finds  a water-line  for  each  of  them. 

“The  fact  that  there  are  exact  numerical  relationscon- 
necting  the  spectra  of  different  elements  does  not  afford 
a proof  of  Griinwald’s  hypothesis  ; and,  until  the  above 
difficulties  are  removed,  the  evidence  is  against  it.  But 
even  granting  it,  how  do  we  know  that  a and  b are  not 
themselves  compounds  ? In  the  second  group  of  cad- 
mium lines  there  are  nineteen  lines  which  can  be  trans- 
formed into  b lines  ; b has  many  other  lines  ; so  at  the 
most  this  only  shows  that  cadmium  and  b have  a common 
constituent,  unless,  of  course,  the  absence  of  the  other 
cadmium  lines  is  accounted  for  in  Griinwald’s  own  way 
of  varying  intensity. 

“ The  lines  of  the  spectrum  of  any  one  substance,  as 
carbon  or  iron,  seem  to  fall  into  definite  series  or  groups ; 
and  the  wave-lengths  of  the  lines  in  these  groups  can  be 
expressed  by  formulas,  as  is  well  known.  All  that  the 
fact  of  there  being  a connection  between  the  spectra  of 
different  substances  seems  to  show  is  then,  that  there 
may  be  a formula  common  to  many  elements,  as  Kayser 


208 


THE  PERIODIC  LAW. 


and  Runge  have  recently  found.  Andall  that  this  means 
is  that  the  molecules  of  these  elements  vibrate  in  general 
according  to  a similar  law.  ’ ’ 

138.  Qruenwald’s  Definition  of  Chemical  Atoms. — It 
is  perhaps  in  place  to  give  here  Griinwald’s  definition 
of  chemical  atoms  (176)  : A chemical  atom  is  a com- 
plex of  exceedingly  many  moveable  particles,  which  are 
elastic,  but  so  intimately  connected  together  that  no 
chemical  process  which  comes  under  our  consideration 
is  capable  of  severing  this  union  and  breaking  the  atom 
into  fragments.  The  parts  of  the  atom  are  not  conceived 
of  as  absolutely  immutable  any  more  than  the  atom 
itself,  but  as  capable  within  finite  limits  of  under- 
going modifications,  which  have  definite  relations  to 
their  mutual  reactions. 

“According  to  this  view  an  atom  may  have  a spectrum 
consisting  of  very  numerous  rays  of  different  wave-lengths. 
This  spectrum  varies  according  to  fixed  laws,  when  the 
chemical  condition  of  the  substance  consisting  of  such 
atoms  and  its  relations  to  other  substances  vary.  It  is 
not  impossible,  and  even  probable,  that  the  particles  of 
an  atom  are  identical  with  the  particles  of  the  ether,  or 
with  condensation  forms  of  the  ether.  It  will  be  easily 
seen  that  in  an  intimate  union  of  two  atoms,  in  which 
they  combine  each  with  one  or  with  several  adjacent 
particles,  the  latter,  which  possibly  in  the  free  condition 
of  the  atoms  perform  vibrations  of  different  periods,  after 
the  chemical  combination  of  the  atoms,  vibrate  in  an  ac- 
cordant manner,  and  may  thus  become  true  moveable 
nodal  points  or  ramification  points  of  the  molecules  of 


THOMSEN’S  VIEWS. 


209 


the  compound  in  question.  This  will  find  its  expression 
in  the  spectrum  of  the  compound  in  such  a manner  that 
it  will  have  rays  belonging  to  each  component ; on  the 
disruption  of  the  compound  they  will  generally  be  re- 
solved into  two  rays  of  different  periods,  one  of  which 
belongs  to  the  spectrum  of  one  of  the  constituents  now 
set  free,  and  the  other  ray  to  the  spectrum  of  the  other 
constituent.” 

139.  Thomsen’s  Views  as  to  the  Unity  of  Matter. — It 

is  a striking  fact  that  two  such  distinguished  chemists 
as  Thomsen  and  Wislicenus  should,  in  the  latter  part  of 
this  century  deem  it  especially  fitting  in  commemoration  of 
historical  anniversaries  of  their  respective  universities 
to  give  expression  to  their  views  as  to  the  unity  of  mat- 
ter. Thomsen  (168)  first  reviews  the  history  of  this 
great  idea.  Then  he  takes  up  the  question  for 
himself  as  to  whether  all  of  the  seventy  elements, 
now  recognized,  are  to  be  looked  upon  as  one  kind 
of  matter.  The  plausibility  of  this  hypothesis  is 
discussed  from  the  standpoint  of  the  distribution  of  the 
elements  ; the  comparison  of  them  with  the  compound 
radicals  ; the  vast  number  of  organic  compounds  which 
are  made  up  of  four  of  these  elements  only  ; the  close 
approximation  of  the  atomic  weights  to  integral  numbers ; 
the  dependence  of  the  properties  upon  the  atomic  weights ; 
the  fact  that  some  of  these  elements  have  been  separated 
into  others,  as  didymium  ; and  the  hope  of  further  suc- 
cess along  the  line  of  fractional  precipitation.  He  noted 
that  the  atomic  weights  were  not  consecutive  whole 
numbers  but  often  differ  by  a few  units.  Like  de  Chan- 


210 


THE  PERIODIC  LAW. 


courtois  and  Meyer  he  imagined  these  elements  upon  a 
symmetrical  cylinder,  the  elements  of  the  same  valence 
falling  in  vertical  columns.  The  temperature  of  the  sun, 
he  thought,  ought  to  decompose  the  elements,  at  least 
as  far  as  the  atoms  and  perhaps  to  the  elementary  mat- 
ter. The  helium  line,  seen  in  the  sun’s  spectrum,  must 
be  lighter  than  hydrogen  and  may  be  the  stuff  out  of 
which  all  the  others  are  formed.  Something  like  this 
temperature  might  be  obtained  by  concentrating  the 
sun’s  rays.  The  isolation  of  the  elementary  matter 
would  be  a very  difficult  problem,  however,  the  isolation 
of  the  ordinary  elements  being  often  very  difficult. 
Lastly,  he  compared  the  change  of  matter  from  one  kind 
to  another  with  the  problem  of  the  biologist  witli  regard 
to  the  change  of  series. 

140.  A Function  expressing  the  Periodicity  of  the 
Elements  by  Flavitzky . — The  graphical  representations 
of  the  periodic  law  by  Bayley,  vouHuth,  Spring  and  Rejr- 
noldsare  all  mentioned  by  Flavitzky  as(  1 66 ) curves  which 
cannot  be. represented  by  simple  mathematical  equations. 
The  discovery  of  the  equation  would  enable  one  to  ac- 
curately determine  the  atomic  weight  and  therefore  he 
attempted  to  give  an  approximate  solution  of  the  problem. 
For  this  purpose  he  divided  the  elements  up  into  periods, 
the  first  containing  the  7 + 7 elements  from  lithium 
to  chlorine.  The  properties  of  these  are  discussed  and 
compared.  The  second  period  consists  of  7 + 3 + 7. 

Sine  and  cosine  functions  will  not  do  for  the  Periodic 
Law,  among  other  reasons,  because  the  values  do  not 
change  sign  -f-  or  — in  passing  through  o°.  Flavitzky 


flavitzky’s  function. 


21 1 


says  the  periodic  law  must  be  represented  by  some  func- 
tion of  tangent  or  cotangent.  If  these  functions  are 
used,  then  the  periodic  law  can  be  graphically  repre- 


sented by  a circle  or  curve  with  a circumference  in  which 
seven  elements  would  be  found  in  the  first  semi-circum- 
ference and  seven  in  the  second.  The  diagram  will  make 
this  clear.  The  function  decided  upon  is  then  given  as 


212 


THE  PERIODIC  LAW. 


a cot  g 2 7T  <p  (p)  where  a is  a constant  depending  on 
the  properties  which  so  far  have  not  been  expressed 
numerically  and  q>  (p)  is  dependent  on  the  atomic 
weight.  Neglecting  the  oo  value  of  the  conta- 
gent  when  the  angle  is  o°  he  assumed  the  first  semi- 
circumference as  having  a value  of  37 — 1.4=35.6. 


Taking  the  equation  a cot  g 2tt 


,P— 1.4 


and  solving  it  so 


35-6 

= 10.3  and  this  value 


that  a cot — - = o,  he  found  that  p 
2 

lies  between  beryllium  and  boron.  Therefore,  in  the 
first  quadrant  there  are  two  elements  lithium  and 
beryllium,  leaving  in  the  second  quadrant  the  remaining 
five.  Similarly  when  a cot  7r  = 00 ; p = 19.2  that  is  just  be- 
yond the  atomic  weight  of  fluorine.  Continuing  around  the 

37T 

circumference,  a cot— = 0,  when  p—  28.1  ; that  is,  be- 
tween silicon  and  phosphorus  and  finally  a cot  2 n = 00  when 
p—Zl-  The  next  period  is  worked  out  in  like  manner. 

The  function  fails  wfith  the  eighth  group  and  after  caesi- 
umall  is  more  or  less  guess-work.  The  figure  is  not  drawn 
to  scale  but  is  merely  intended  to  show  something  of  the 
nature  of  the  graphic  representation.  Instead  of  giving 
only  two  elements  in  the  first  quadrant,  as  stated  above, 
three  are  given.  In  discussing  the  diagram  he  connected 
the  changes  in  the  electropositive  or  negative  character 
of  the  elements  in  the  various  groups  with  the  changes 
in  the  sign  of  the  cotangent  from  o°  to  90°  +;  from  90°  to 
1800 — ; etc.,  and  we  have  a repetition  of  these  signs  as  the 
darius  vector  sweeps  out  a larger  and  larger  circular 


NUMERICAL  REGULARITIES. 


213 


angle.  The  lack  of  strict  repetition  of  properties  in  the 
higher  periods  he  assumed  to  be  due  to  the  greater  com- 
plexity of  the  molecules  of  the  elements  with  higher 
atomic  weights,  the  non-correspondence  strictly  of  sodium 
with  copper,  silver,  and  gold  being  cited.  He  added 
some  speculations  as  to  the  cause  of  valence  and  chemical 
affinity,  assuming  that  the  molecules  were  not  all  mov- 
ing in  the  same  or  parallel  planes  and  further  in  these 
planes  the  molecules  move  either  clockwise  or  counter- 
clockwise and  that  when  two  elements  combine  the 
motions  of  the  molecules  take  place  in  planes  more  or 
less  inclined  to  each  other.  He  elaborated  this  idea  and 
pictured  the  relative  planes  in  which  the  atoms  are  as- 
sumedtomove.  Thussodiumand  fluorine  are  in  parallel 
planes  but  the  motions  are  opposed.  He  supposed  that 
when  the  planes  in  which  two  elements  move  are  not  paral- 
lel, the  contrary  motions  are  resolved,  so  that  the  com- 
ponent motion  parallel  to  the  other  plane  causes  the 
affinity.  This  speculation  is  purely  tentative. 

141.  Numerical  Regularities  observed  by  Bazaroff. — 
The  author  (167)  found  that  the  variation  in  the  num- 
bers expressing  the  atomic  weights  of  the  elements,  ar- 
ranged according  to  the  periodic  system,  is  analogous  to 
the  changes  in  the  properties  of  the  elements  and  their 
compounds. 

In  the  periodic  system  of  the  elements,  either  in  the 
vertical  or  horizontal  lines,  if  the  atomic  weight  of  an 
element  be  divided  by  that  of  the  element  having  the 
next  lower  atomic  weight,  products  are  obtained  which 
decrease  regularly  with  the  increase  in  the  atomic  weights 


214 


THE  PERIODIC  LAW. 


compared.  In  the  horizontal  series  the  maximum  is  found 

Be  _ 9.08 


to  correspond  with  the  ratio 


Li 


7.01 


= 1-2953.  the 


minimum  with 


Bi  _ 207.5 


1.0054.  This  decrease  is 


Pb  206.30 

not  continuous,  there  being  alternate  decrease  and  in- 


crease 


: Thus  1. 

Na 


A1 


Si 


041 1;  m^=i-I295:  a!  = i-°355; 


— =1.1057  etc.  Represented  graphically  this  gives  a 

ol 

zigzag  curve  (atomic  weights  as  abscissae,  quotients  as 
ordinates.)  The  author  expressed  this  as  a law  thus  : 
“the  increase  in  the  atomic  weights  of  the  elements  pro- 
ceed, with  a variable  intensity,  the  smaller  coefficient  of 
change  varying  with  the  larger  in  such  a way  that  both 
regularly  decrease.’’ 

Another  regularity  is  observed  in  the  vertical  groups, 
for  example,  with  the  coefficients  in  the  second  groups. 

The  author  expressed  this  change  by  another  law  ‘ ‘ In 
the  vertical  series  in  the  periodic  system,  the  relations 
of  two  neighboring  atomic  weights,  decreases  with  in- 
creasing atomic  weight,  but  this  decrease  is  alternately 
larger  and  smaller.’’ 

Neither  of  these  laws  extend  to  the  entire  system  as 
many  of  the  atomic  weights  are  too  imperfectly  known  as 
yet.  Still  the  author  regarded  it  as  possible  to  state  the 
following  general  law  : “ The  magnitude  of  the  atomic 
weight  of  each  element  is  determined  by  the  magnitude 
of  the  atomic  weights  of  the  elements  next  to  it  in  the 
periodic  system  both  horizontally  and  vertically.’’  Not- 


LIVERMORE’S  CLASSIFICATION. 


215 


withstanding  the  apparently  complicated  character  of 
the  relation  pointed  out,  the  author  thinks  that  “ when 
the  fundamental  data  are  more  exactly  determined,  it 
may  be  possible  to  calculate  the  atomic  weight  of  an 
element  with  greater  accuracy  than  is  the  case  at 
present.” 

142.  Livermore’s  Classification. — The  classification 
offered  by  Livermore  (171)  is  based  upon  the  divisibility 
of  the  atomic  weight  by  two,  in  conjunction  with  the  in- 
crease in  these  weights.  The  object  is  to  contribute  to 
the  removal  of  the  difficulties  urged  by  Wurtz  against 
the  Periodic  Law,  namely  that  the  atomic  weights  of  suc- 
cessive elements  vary  within  considerable  limits  without 
displaying  any  regularity  in  these  variations  and  that  the 
graduations  in  properties  do  not  seem  to  depend  upon  the 
degree  of  the  differences  between  the  atomic  weights. 

The  series  were  first  examined  for  evidences  of  a con 
stant  increase.  Using  4 as  a modulus,  he  secured  two 
series  : 

7,  11,  *,  19,  23,  27,  31,  39,  x,  x,  51,  55,  59, 

12,  16,  28,  32,  jv,  40,  44,  48,  52,  56. 

This  embraces  in  two  parallel  series  all  the  terms  of 
the  first  three  periods  of  Nervlands  and  Mendeleeff  with 
the  exception  of  9,  and  14,  that  is  twenty-two  out  of  the 
twenty-four.  These  two  series  coincide  with  the  peris- 
sads  and  artiads  already  distinguished  by  chemists  be- 
cause of  their  uneven  and  even  quantivalence.  He 
therefore  called  it  the  Perissad  Law.  By  similar  methods 
the  numbers  between  70  and  100  fall  into  two  series 
with  a common  difference  of  5 for  the  perissads  and  per- 


216 


THE  PERIODIC  LAW. 


haps  4 for  the  artiads  (the  latter  series  indefinite. ) Be- 
tween iooand  150  the  perissads  increase  regularly,  with 
a common  difference  of  about  6^  and  the  artiads  less  reg- 
ularly with  the  same  difference. 

Beyond  this  the  author  thought  the  atomic  weights 
were  too  imperfectly  known  for  accurate  classification. 
The  fact  that  these  arrangements  apparently  throw  cobalt, 
nickel,  and  mercury  out  of  their  proper  groupings  was 
mentioned.  Tables  are  given  containing  the  serial 
numbers,  the  observed  atomic  weights  and  the  devia- 
tions from  the  serial  numbers.  Other  columns  show  the 
specific  gravity,  the  atomic  volume,  the  fusibility,  mal- 
leability and  other  properties.  The  possibility  of  the 
existence  of  elements  with  the  atomic  weights  15,  43, 
or  44,  47,  60,  and  perhaps  of  99,  100 ’and  143  is  inferred 
from  analogy. 

The  formula  for  calculating  the  atomic  weights  is 
a -f-  nd  and  it  has  the  following  values  for  the  several 
groups  of  common  differences,  6.99  -f-  n X 4.02  ; 
12.00-I -?i  X 4.01  ; 70.25  -j-  n X 4.85  ; 74.88  -(-  « X 4.12 
107.85  -\-n  X 6.20  ; 105.98  -f-  n X 6.22. 

A good  deal  of  importance  seems  to  be  attached  to  the 
electro-chemical  factors  assigned  to  each  element.  The 
bearing  of  these  is  not  very  clear. 

143.  An  Atomic  Hypothesis  by  Pearson. — This  paper 
(172)  is  largely  mathematical,  dealing  in  the  nature 
and  motion  of  the  atoms.  Simple  numerical  relations, 
periodicity,  etc.,  are  not  taken  into  consideration. 

144.  Johnstone  Stoney’s  Logarithmic  Law  of  the 
Atomic  Weights. — This  memoir  (173)  is  divided  into 
five  sections: 


LOGARITHMIC  LAW  OF  ATOMIC  WEIGHTS. 


217 


Section  1 . Shows  that  it  is  impossible  to  discuss  the 
mathematical  relations  between  the  successive  atomic 
weights  by  plotting  down  the  atomic  weights  as  ordinates 
and  allowing  the  abscissae  to  represent  some  simple 
numerical  series.  The  curve  would  be  represented  by 
the  equation  y = k (log  x )*  where  a-  does  not  represent 
simple  integral  numbers  but  a circular  function  of  them. 
The  method  is  therefore  a hopeless  one. 

Section  2.  Here  successive  atomic  weights  are  re- 
presented not  by  lines  but  by  volumes.  A succession 
of  spheres  are  taken  whose  volumes  are  proportional  to 
the  atomic  weights  (atomic  spheres.)  When  the  radii 
of  these  spheres  are  plotted  as  ordinates  and  a series  of 
integers  as  abscissae,  the  general  form  of  the  logarithmic 
curve  y — k log  (gx)  becames  apparent.  Close  scrutiny 
has  shown  that  this  expresses  the  law  of  nature.  It  is 
the  central  curve  that  threads  its  way  through  the  posi- 
tions given  by  observations  and  the  deviations  from  it  of 
the  positions  assumed  by  the  actual  atomic  weights  will 
be  included  by  making  x a circular  function  of  integral 
numbers,  instead  of  those  numbers  themselves.  The 
issue  of  the  investigation  is  to  show  that  when  such  a 
diagram  is  formed  with  ordinates  which  are  the  cube 
roots  of  the  atomic  weights,  referred  to  hydrogen  as 
unit,  so  that  the  ordinates  may  be  the  radii  of  spheres 
whose  volumes  represent  the  atomic  weights,  then : 

1.  The  logarithmic  curve y—  k log  (ma) , log  k = 
0.785,  log  a = 1.986,  threads  its  way  through  the  posi- 
tions plotted  down  from  the  observations. 


2l8 


THE  PERIODIC  LAW. 


2.  In  the  ease  of  the  perissads,  the  complete  curve 
which  includes  their  perturbations  from  the  central  curve 

is  ym—  k log  sin--*_- -j- ^ sin-^g-  -{-  subse- 

quent terms),  the  next  term  being  probably  either — ^sin 

771  Tt  . mn 

- or  — 4 sm . 

9 9 

3.  The  form  of  the  function  representing  the  perturba- 
tions of  the  artiads  is  different,  at  all  events,  after  the 
third  term. 

Section  3.  There  are  other  neighboring  curves  (log- 
arithmic) which  pursue  a course  close  to  the  observed 
position  and  the  method  adopted  in  dealing  with 
these  curves  is  described  and  the  grounds  on  which  they 
have  been  successively  excluded  are  stated.  The  evi- 
dence relied  on  has  been  for  the  most  part,  that  the 
perturbations  from  them  are  less  reducible  to  order. 

Section  4.  The  curve  finally  selected  is  thrown  into  a 
polar  form  and  furnishes  a diagram  for  laboratory  use. 
“ It  presents  conspicuously  the  information  which  the 
Mendeleeff  table  is  capable  of  supplying  with  the  further 
advantage  of  placing>  before  the  eye  an  intelligible  rep- 
resentation of  the  atomic  weights.” 

145.  New  Relations  between  the  Atomic  Weights  ob= 
served  by  Delauney. — In  his  first  paper  (174)  Delauney 
states  that  if  the  equivalent  of  hydrogen  be  taken  as 
unit  the  equivalents  of  the  other  elements  are  repre- 
sented by  the  expression  in  which  AT  and  n 

are  whole  numbers,  the  value  of  n being  o,  1,  2,  3.  or  4. 


ILLUSTRATIONS  OF  THE  PERIODIC  LAW.  2ig 

The  calculated  numbers  agree  fairly  well  with  actual 
determinations.  The  elements  may  be  divided  into 
groups  or  families  according  to  the  values  of  n,  but  the 
same  element  may  fall  into  two  or  even  three  families. 
N 

The  omission  of—  merely  changes  the  unit  of  equiva- 
lence, and  hence  only  the  simplified  expression-^  s2 n 2 

need  be  considered. 

The  author  supposed  the  existence  of  a primitive  mole- 
cule composed  of  five  atoms  revolving  at  different  dis- 
tances around  a central  atom  after  the  manner  of  planets 
around  the  sun.  If  such  a system  is  penetrated  by  a 
group  of  atoms,  all  tangent  to  one  another,  the  opposite 
directions  of  their  motions  will  give  rise  to  a stress  which 
will  result  in  an  agglomeration  of  the  atoms. 

In  another  paper,  Delauney  (186)  observed  that  when 
the  elements  are  arranged  in  the  order  of  their  atomic 
weights  each  atomic  weight  differs  from  that  immediately 
preceding  it  by  the  square  root  of  a whole  number. 
This  number  is  variable,  but  is  always  harmonic,  that 
is,  contains  as  primary  factors  only  the  numbers  i,  2,  3, 
and  5. 

146.  Haughton’s  Geometrical  Illustrations  of  the 
Periodic  Law. — This  work  (175)  is  based  upon  the  dia- 
gram of  Reynolds.  Taking  the  first  fourteen  elements 
and  eliminating  C,  N,  O,  Mg,  and  Si  as  being  upon  a 
straight  line,  a serpentine  cubic  curve  may  be  drawn 
through  the  remainder.  (See  figures  1 and  2.)  Simi- 
larly for  the  second  fourteen,  five  are  found  upon  a 


Figure  i.  (Haughton). 

hexad 


2 20 


THE  PERIODIC  LAW 


ILLUSTRATIONS  OF  THE  PERIODIC  LAW 


221 


Figure  2.  (Haughton.) 


Figure  3.  (Haughton). 


222 


THE  PERIODIC  LAW 


Figure  4.  (Haughton). 


illustrations  of  the  periodic  law. 


223 


224 


THE  PERIODIC  LAW. 


straight  line,  namely  Ti,  V,  Ca,  Ga,  and  Ce.  A much 
more  complex  cubic  curve  can  be  drawn  through  the 
remainder.  (See  figures  3 and  4). 

The  relationships  of  these  elements  as  exemplified  by 
the  curves,  are  pointed  out.  The  position  of  hydrogen 
is  discussed  and  Fe,  Ni,  Co,  are  taken  from  the  places 
assigned  by  Mendeleeff  and  placed  next  to  chromium. 
The  possibility  of  the  existence  of  other  elements  is  sug- 
gested as,  for  instance,  one  of  the  atomic  weight  50  and 
one  of  69.5. 

147.  Hartley’s  Definition  of  Atomic  Weight. — An 

atomic  weight  is  a numerical  proportion.  There  are  sev- 
enty elements  and  seventy  atomic  weights  and  the  serep- 
resent  matter  in  seventy  different  states  of  condensation. 

The  author  (177)  would  recommend  the  following 
definition  : The  atomic  weight  of  an  element  is  the  ratio 
of  the  mass  of  its  atoms  to  the  mass  of  an  atom  of  hydro- 
gen. The  term  atomic  weight  should  be  abolished  and 
atomic  mass  substituted.  Similarly,  molecular  weight 
should  be  defined  as  the  mass  of  a molecule  or  molecular 
mass.  The  mass  of  a molecule  is  the  sum  of  the  masses 
of  its  constituent  parts. 

The  Periodic  Law  can  then  be  thus  stated : The 
properties  of  the  atoms  are  a periodic  function  of  their 
masses.  In  any  graphic  representation  of  the  periodic 
law  the  fact  that  it  is  upon  the  mass  of  the  atoms  that 
their  properties  depend  should  appear  prominently. 
The  diagram  of  Dr.  Johnstone  Stoney  used  to  illustrate  the 
“ Logarithmic  Law  of  Chemistry”  has  on  this  account 
alone  a preeminent  importance. 


REMSEN  ON  THE  NATURE  OF  THE  ELEMENTS.  225 

148.  Stransky’s  Numerical  Relations. — Such  numeri- 
cal relations  as  the  following  are  given  by  Stransky  (180) 
: 5+ 2X  2 = 7 (Li)  ; 5 + 5 X 2 = 9 (Be)  ; 5 + 3X2 
— 11(B);  etc.  10  -(-  1 X 2 = 12  (C)  ; 10  + 2X2  = 14 
(N);  10  -f-  3X2  = 16  (O). 

The  following  relation  is  then  stated  : “ The  atomic 
weights  of  the  elements  of  any  natural  group  are  rational 
multiples  of  that  of  the  first  member  of  the  series  minus 
a constant  or  some  number  regularly  increasing  in 
arithmetical  progression.”  From  the  table  given  below 
it  can  be  deduced  that  the  atomic  weights  of  elements 
of  any  natural  group  are  rational  multiples  also  of  the 
second  member  of  the  series,  minus  a constant  or  some 
number  regularly  increasing  in  arithmetical  progression. 


Li 

7 

1X7  = 7 

Na  23 

4X7—  5=23 

1X23  =23 

K 

39 

7X7—10=39 

2X23—7=39 

Cu  63 

11X7—15=62 

3X23—7=62 

Rb  85 

15X7—20=85 

4X23—7=85 

&c. 

&c. 

&c. 

149.  Remsen  on  the  Nature  of  the  Elements. — In  a 

lecture  upon  the  ‘‘Chemistry  of  To-day”  (183)  this  au- 
thor says  : ‘‘It  has  been  shown  by  a Russian  chemist, 
Mendeleeff,  and  at  the  same  time  by  a German,  Lothar 
Meyer,  that  the  elements  are  related  in  a very  remarkable 
way,  so  closely  that  it  is  possible  to  arrange  them  all  in 
one  table,  in  which  they  form  parts  of  a system  general. 
The  law  governing  the  variations  in  properties  of  the  ele- 
ments is  known  as  the  Periodic  Law.  The  limits  of  this 
article  will  not  permit  any  detailed  explanation  of 


226 


THE  PERIODIC  LAW. 


this  remarkable  law.  The  main  point  that  I wish 
to  emphasize  is,  that  the  so-called  elements  are  shown 
to  be  related  to  one  another,  and  it  seems  impos- 
sible in  the  light  of  these  facts,  to  believe  that  they 
are  distinct  forms  of  matter.  It  seems  much  more 
probable  that  they  are  in  turn  composed  of  subtler 
elements  and  it  has  been  pointed  out  that  all  the 
substances  which  we  now  call  elements,  of  which  there 
are  about  seventy,  can  be  conceived  to  be  made  of  two 
fundamental  elements  combined  in  different  proportions. 
There  does  not,  however,  appear  to  be  any  immediate 
prospect  of  discovering  these  fundamental  substances.” 

150.  Mendeleeff’s  Faraday  Lecture. — This  lecture, 
delivered  before  the  London  Chemical  Society  in  1889, 
‘‘passing  in  review  the  twenty  years’  life  of  the  gen- 
eralization which  is  known  under  the  name  of  the 
Periodic  Law,”  is  an  exceedingly  valuable  contribution 
to  the  history  of  this  system.  It  gives  a brief  sum- 
mary of  the  work  which  preceded  his,  and  then  of 
his  own  beginnings  ; it  gives  his  criticisms  of  the  work 
of  those  who  have  followed  him  and  something  of  his 
views  as  to  the  future  development  of  the  law. 

A portion  of  the  lecture  is  devoted  to  proving  that  it 
is  not  possible  by  the  ordinary  curves  and  mathematical 
formulas  to  properly  represent  the  periodicity  which  is, 
according  to  the  law,  to  be  observed  between  the  proper- 
ties of  the  atoms.  In  the  first  place,  as  Hartley  has  em- 
phasized, this  periodicity  exists  between  the  masses  of 
the  atoms.  ‘ ‘ All  that  was  known  of  functions  dependent 
on  masses  derived  its  origin  from  Galileo  and  Newton, 


MENDELEIEFF’S  FARADAY  LECTURE.  227 

and  indicated  that  such  functions  either  decrease  or  in- 
crease with  the  increase  of  mass,  like  the  attraction  of  ce- 
lestial bodies.  The  numerical  expression  of  the  phenom- 
ena was  always  found  to  be  proportional  to  the  mass,  and 
in  no  case  was  an  increase  of  mass  followed  by  any  recur- 
rence of  property  such  as  is  disclosed  by  the  Periodic  Law 
of  the  elements.  This  constituted  such  a novelty  in  the 
study  of  the  phenomena  of  nature  that  although  it  did  not 
lift  the  vail  which  conceals  the  true  conception  of  mass,  it 
nevertheless  indicated  that  the  explanation  of  the  concep- 
tion must  be  searched  for  in  the  masses  of  the  atoms. 

“Now  natural  science  has  long  been  accustomed  to  deal 
with  periodicities  observed  in  nature,  to  seize  them  with 
the  vice  of  mathematical  analysis,  to  submit  them  to 
the  rasp  of  experiment.  And  these  instruments  of 
scientific  thought  would  surely  long  since  have  mastered 
the  problem  connected  with  the  chemical  elements,  were 
it  not  for  a new  feature  which  was  brought  to  light  by 
the  Periodic  Law  and  which  gave  a peculiar  and  original 
character  to  the  periodic  function.  If  we  mark  on  an 
axis  of  abscissae  a series  of  lengths  proportional  to 
angles  and  trace  ordinates  which  are  proportional  to 
sines  or  other  trigonometrical  functions,  we  get  periodic 
curves  of  a harmonic  character.  So  it  might  seem,  at 
first  sight,  that  with  the  increase  of  atomic  weights  the 
function  of  the  properties  of  the  elements  should  also 
vary  in  the  same  harmonious  way.  But  in  this  way 
there  is  no  such  continuous  change  as  in  the  curves  just 
referred  to,  because  the  periods  do  not  contain  the  in- 
finite number  of  points  constituting  the  curve,  but  a 


228 


THE  PERIODIC  LAW. 


finite  number  only  of  such  points.  An  example  will 
better  illustrate  this  view.  The  atomic  weights  of 
certain  elements  steadily  increase,  and  their  increase  is 
accompanied  by  a modification  of  many  properties  which 
constitutes  the  essence  of  the  Periodic  Law.  But  to  con- 
nect by  a curve  the  summits  of  the  ordinates  expressing 
any  of  these  properties  would  involve  the  rejection  of 
Dalton’s  law  of  multiple  proportions.  Not  only  are  there 
no  intermediate  elements  but,  according  to  the  very 
essence  of  the  Periodic  Law  there  can  be  none  ; in  fact  a 
uniform  curve  would  be  inapplicable  in  such  a case,  as 
it  would  lead  us  to  expect  elements  possessed  of  special 
properties  at  any  point  of  the  curve.  The  periods  of  the 
elements  have  thus  a very  different  character  from  those 
which  are  so  simply  represented  by  geometers.  They 
correspond  to  points,. to  numbers,  to  sudden  changes  of 
the  masses  and  not  to  a continuous  evolution.  In  these 
sudden  changes,  destitute  of  intermediate  steps  or  posi- 
tions, in  the  absence  of  intermediate  elements,  we  must 
recognize  a problem  to  which  no  direct  application  of 
the  infinitely  small  can  be  made.  Therefore,  neither 
the  trigonometrical  functions  proposed  by  Rydberg  and 
Flavitzky,  nor  the  pendulum-oscillations  suggested  by 
Crookes,  and  the  cubical  curves  of  Haughton,  which 
have  been  proposed  for  expressing  the  periodic  law, 
from  the  nature  of  the  case,  can  represent  the  periods  of 
the  chemical  elements.  If  geometrical  analysis  is  to  be 
applied  to  this  subject  it  will  require  to  be  modified  in  a 
special  manner..” 

He  spoke  of  the  efforts  of  Mills  and  Tchitcherine  to  ex- 


MENDELfiEFF’S  FARADAY  LECTURE.  229 

press  the  atomic  weights  of  the  elements  by  means  of 
algebraic  formulas  but  regarded  them  as  incomplete  and 
said  that  attempts  like  these  must  be  multiplied.  As  to 
Bockyer’s  hypothesis  he  said  that  it  “evidently  must 
have  arisen  from  a misunderstanding.  The  spectrum 
of  a compound  body  certainly  does  not  appear  as  a sum 
of  the  spectra  of  its  components  ; and  therefore  the 
observations  of  Bockyer  can  be  considered  precisely  as 
a proof  that  iron  undergoes  no  other  changes  at  the 
temperature  of  the  sun  but  those  which  it  experiences 
in  the  voltaic  arc,  provided  the  spectrum  of  iron  is  pre- 
served. As  to  the  shifting  of  some  of  the  lines  of  the 
spectrum  of  iron  while  the  other  lines  maintain  their 
positions,  it  can  be  explained,  as  shown  by  M.  Kleiber1 
by  the  relative  motion  of  the  various  strata  of  the  sun’s 
atmosphere,  and  by  Zollner’s  laws  of  the  relative 
brilliancies  of  different  lines  of  the  spectrum.  Moreover, 
it  ought  not  to  be  forgotten  that  if  iron  really  proved  to 
consist  of  two  or  more  unknown  elements,  we  simply 
should  have  an  increase  of  the  number  of  our  elements, 
not  a reduction  and  still  less  a reduction  of  all  of  them 
to  one  single  primary  matter.” 

As  to  the  criticism  of  the  periodic  law  by  Berthelot, 
he  said  “ he  has  simply  mixed  up  the  fundamental  idea 
of  the  law  of  periodicity  with  the  ideas  of  Prout,  the 
alchemists,  and  Democritus  about  primary  matter. 
But  the  Periodic  Daw,  based  as  it  is  on  the  solid  and 
wholesome  ground  of  experimental  research,  has  been 
evolved  independently  of  any  conception  as  to  the  nature 

1 Journal  of  the  Russian  Chemical  and  Physical  Society  for  1885,  p.  147. 


230 


THE  PERIODIC  LAW. 


of  the  elements ; it  does  not  in  the  least  originate  in  the 
idea  of  an  unique  matter  and  it  has  no  historical  connec- 
tion with  that  relic  of  the  torments  of  classical  thought, 
and  therefore  it  affords  no  greater  indication  of  the  unity 
of  matter  or  of  the  compound  nature  of  our  elements, 
than  the  law  of  Avogadro,  or  the  law  of  specific  heats, 
or  even  the  conclusions  of  spectrum  analysis.  None  of 
the  advocates  of  an  unique  matter  have  ever  tried  to  ex- 
plain the  law  from  the  standpoint  of  ideas  taken  from  a 
remote  antiquity  when  it  was  found  convenient  to  admit 
the  existence  of  many  gods,  and  of  an  unique  matter.” 
Referring  to  the  comparison  of  Pelopidas  and  others  of 
the  periodic  system  of  the  elements  with  the  homologous 
series  of  the  hydrocarbon  radicals,  he  wrote  : “ The 
most  important  consequence  which,  in  my  opinion,  can 
be  drawn  from  the  above  comparison  is,  that  the  Periodic 
Law,  so  apparent  in  the  elements,  has  a wilder  applica- 
tion than  might  appear  at  first  sight ; it  opens  up  a new 
vista  of  chemical  evolutions.  But,  while  admitting  the 
fullest  parallelism  between  the  periodicity  of  the  elements 
and  that  of  the  compound  radicals,  we  must  not  forget 
that  in  the  periods  of  the  hydrocarbon  radicals  we  have 
a decrease  of  mass  as  we  pass  from  the  representative  of 
the  first  group  to  the  next,  wdiile  in  the  periods  of 
the  elements  the  mass  increases  during  the  pro- 
gression. It  thus  becomes  evident  that  we  can- 
not speak  of  an  identity  of  periodicity  in  both  cases,  un- 
less we  put  aside  the  ideas  of  mass  and  attraction  which 
are  the  real  cornerstones  of  the  whole  of  natural  science 
and  even  enter  into  those  very  conceptions  of  simple 


MENDEL&EFF’S  FARADAY  LECTURE.  23  I 

bodies  which  came  to  light  a full  hundred  years  later 
than  the  immortal  principles  of  Newton.  From  the  fore- 
going, as  well  as  from  the  failures  of  so  many  attempts 
at  finding  in  experiment  and  speculation  a proof  of  the 
compound  character  of  the  elements  and  of  the  existence 
of  primordial  matter,  it  is  evident,  in  my  opinion,  that 
this  theory  must  be  classed  among  mere  utopias.  But 
utopias  can  only  be  combatted  by  freedom  of  opinion, 
by  experiment,  and  by  new  utopias.  In  the  republic  of 
scientific  theories,  freedom  of  opinions  is  guaranteed. 
It  is  precisely  that  freedom  which  permits  me  to  criti- 
cise openly  the  widely  diffused  idea  as  to  the  unity  of 
matter  in  the  elements.  Experiments  and  attempts  at  con- 
firming that  idea  have  been  so  numerous  that  it  really 
would  be  instructive  to  have  them  all  collected  together, 
if  only  to  serve  as  a warning  against  the  repetition  of 
old  failures.” 

Mendeleeff  spoke  of  his  predictions  and  their  happy 
fulfilment.  He  added  that  ‘‘although  greatly  enlarging 
our  vision,  even  now  the  Periodic  Law  needs  further  im- 
provements in  order  that  it  may  become  a trustworthy 
instrument  in  further  discoveries.”  He  does  not  seem 
to  regard  the  vacant  spaces  in  his  arrangement  or  table 
as  equivalent  to  predictions  of  new  elements  for  he  says, 
11  I foresee  some  more  new  elements,  but  not  with  the 
same  certitude  as  before”  and  then  he  gives  one  example, 
predicting  a di-tellurium  with  an  atomic  weight  of  212. 

In  the  first  chapter  of  the  second  volume  of  his  Princi- 
ples of  Chemistry,  Mendeleeff  gave  much  that  bears 
upon  the  history  of  the  Periodic  Law. 


232 


THE  PERIODIC  LAW. 


15 1.  Buehler’s  Theory  as  to  the  Nature  of  Matter. — 

This  theory  is  based  upon  the  existence  of  an  attracting 
and  a repelling  form  of  matter  aud  the  rotation  of  the 
atoms.  It  is  enunciated  in  opposition  to  the  kinetic 
theory  and  is  intended  to  explain  all  physical  phenomena. 
The  theory  is  brought  to  bear  upon  the  nature  of  the 
ultimate  particles  of  the  chemical  elements.  These  are 
called  primary  atoms. 

From  the  fact  that  many  of  the  atomic  weights  ap- 
proach whole  numbers,  thatis,  are  integral  multiples  of  hy- 
drogen, it  is  assumed  that  these  primary  atoms  are  made 
up  of  a limited  number  of  equally  small  primal  atoms. 
Biihler  then  discusses  the  form  of  one  of  these  primary 
atoms,  supposing  it  to  be  made  up  of  ether-atoms  and 
certain  ponderable  atoms,  whose  nature  is  not  made  clear. 
The  ground  form  of  the  primal  atom  is  octahedral  and  it  is 
made  up  of  ether  and  the  ponderable  matter  in  the  pro- 
portion of  1 to  4-3-.  Covering  these  atoms  there  is  an 
ether  envelope  which  lies  very  closely  upon  the  surface 
of  the  atom.  These  primary  atoms  are  subject  to  a 
rotation. 

The  attraction  of  two  neighboring  atoms,  the  mutual 
influence  of  rotating  atoms,  and  other  points  connected 
with  them  are  discussed  fully  and  with  the  aid  of  mathe- 
matics. The  theory  is  extended  to  the  heavenly  bodies. 


CHAPTER  VIII. 

THE  DEVELOPMENT  FROM  1 890  TO  1895. 

152.  The  Controversy  over  the  Standard. — This  period 
may  be  said  to  begin  with  a controversy  over  the  proper 
standard  for  the  atomic  weights.  The  uncertainty  as  to 
the  oxygen-hydrogen  ratio  gave  rise  to  this  discussion. 
With  each  fresh  revision  of  the  ratio,  giving  a new  value 
for  oxygen,  a great  many  of  the  atomic  weights  of  the 
other  elements  would  require  re-calculation,  so  long  as 
hydrogen,  equal  to  unity,  was  taken  as  the  standard. 
The  discussion  was  opened,  almost  simultaneously,  by 
independent  papers  by  Brauner  (178,  190)  and  Venable 
(179)  and  itwasjoined  inbyOstwald  ( 1 9 1 ) , Noyes  (197), 
and  by  Meyer  and  Seubert,  (189)  the  latter  two  alone 
taking  up  the  defense  of  the  old  standard  hydrogen. 

The  practical  result  of  the  controversy  has  been  the  adop- 
tion of  oxygen  as  the  standard  with  an  atomic  weight 
of  sixteen,  thus  avoiding  a fluctuating  value  for  the  ele- 
ment most  used  in  determining  the  ratios  of  the  others. 

153.  Kronberg’s  Hypothesis  as  to  the  Isomorphism  of 
the  Atoms. — The  author  claimed  to  have  discovered,  in 
1S83,  his  “ cubiponderalgesetz”  as  a law  of  the  natural 
groups  of  equivalent  elements.  The  law  is  stated  thus: 
1 ‘ The  cube  roots  of  the  atomic  weights  of  elements  from 
the  natural  groups  of  equi-valent  elements,  whose  com- 
pounds show  isomorphism,  are  simple  multiples.” 

The  numbers  giving  the  simple  multiples  are  called 
“ specific  atom-factors.”  This  is  peculiarto  each  chemi- 
cal element.  To  explain  this  law  an  hypothesis  of 


234 


THE  PERIODIC  LAW. 


“atom-isomorphism”  is  formulated,  namely,  that  the 
atoms  of  different  elements  from  the  natural  groups  of 
equivalent  elements  whose  compounds  show  isomorphism 
are  themselves  of  geometrically  like  form  and  are 
distinguished  mainly  by  their  relative  size,  which  in- 
creases in  ratios  of  simple  multiples  and  which  only  the 
specific  nature  of  the  element,  besides  the  geometric 
form,  determines. 

There  would  then  be  no  necessity  for  the  supposition 
of  a special  chemical  force.  The  atomic  weight  and  the 
universal  gravitation  of  matter  suffice  to  account  for  all 
phenomena.  The  new  law  and  hypothesis,  the  author 
says,  afford  to  physics  and  chemistry  two  mathematical 
ideas,  in  the  place  of  misty  notions  implied  in  the  so- 
called  natural  groups  of  the  elements  and  in  the  specific 
nature  of  an  element,  ideas  which  shall  give  a mathe- 
matical explanation  and  mode  of  calculation  for  all 
physical  characteristics  of  matter. 

His  table  is  here  repeated  so  as  to  make  the  law  some- 
what clearer. 


TCHITCHERINE’S  SYSTEM. 


235 


Table  for  the  “ Cubiponderalgesetz.” 


Groups  of  equi-valent  ele- 
ments with  isomorphous 
compounds. 


2. — Valent 
alk.  salts. 


Calcium. . 
Strontium 
Barium. . . 


4. — Valent 
carbon 
silicon 
group. 


Carbon. . . . 

Silicon 

Titanium  . 
Zirconium 
Thorium  . 


3 and  5.— Valent 
arsenic  group. 


Arsenic 

Antimony  . . 
Bismuth  . . . 


2 and  6.-Valent 
molybdenum 
group. 


Molybdenum 
Tungsten. . . . 


2 and  4. — Valent 
sulphur  group. 


Sulphur 

Selenium  . . . 
Tellurium  . . 


1. -Valent  f Chlorine 
halogen  < Bromine, 
group.  (Iodine.. 


5^  J 
Atomic 
weights. 

Cubic 

roots. 

Multiples  or  atom  factors. 

Theory. 

Calculated  up- 
on constants. 

39-91 

3-42 

4 

3-42 

4 -=  0.86 

87-3 

4.44 

5 

4-44 

5 =0.89 

136.86 

5-15 

6 

5-15 

6 = 0.86 

11.97 

2.29 

3 

2.29 

3 = 0-76 

28.0 

3-04 

4 

3-°4 

4 = 0 76 

50-25 

3-69 

5 

3-69 

5 — 0.74 

90.4 

4.49 

6 

4.49 

6 = 0.75 

231.96 

6.14 

8 

6.14 

8 = 0.77 

74-9 

4*22 

5 

4-22 

5 = 0.84 

119.6 

4-93 

6 

4-93 

6 = 0.82 

207.5 

5-92 

7 

5-92 

7 = 0-85 

95-9 

4-58 

4 

4-58 

4 = I- 14 

I83.6 

5.68 

5 

5-68 

5 — I-I4 

31.98 

3-17 

3 

3-17 

3 = 1.06 

78.87 

4.29 

4 

4.29 

4 = 1.07 

127.7 

5-°4 

5 

5-°4 

5 = 1 .01 

35-37 

3-28 

4 

3.28 

4 = 0.82 

79.76 

4-31 

5 

4-31 

5 = 0.86 

126.51 

5.02 

6 

5.02 

; 6 = 0.84 

154.  A System  of  the  Elements  by  Tchitcherine. — 

The  first  paper  by  this  author  appeared  in  1888  and  is 
quoted  by  Mendeleeff  in  his  Faraday  Lecture  in  1889 
and  in  the  second  volume  of  his  Principles  of  Chemistry 
The  following  abstract  is  taken  from  a later  publication 
(193)  of  Tchitcherine  in  the  year  1890,  presumably 
more  complete  than  the  earlier  one  which  has  not  been 
accessible  to  the  compiler. 

Taking  the  Periodic  Law  as  a starting  point,  as  given 
in  the  table  of  Mendeleeff,  it  is  first  pointed  out  that 
with  the  increase  in  atomic  weights,  the  elements  pass 
through  periods  of  condensation  and  rarefaction.  Each 
period  of  condensation  commences  with  an  alkali  and 


236 


THE  PERIODIC  LAW. 


each  period  of  rarefaction  terminates  with  the  same. 
Two  consecutive  periods,  one  of  condensation  and  one 
of  rarefaction,  constitute  a great  period  or  cycle.  The 
lengths  of  these  periods,  i.  e.,  the  differences  between 
the  first  and  the  last  atomic  weight,  are  not  equal. 
Thus  the  first  (Lfi-Na)  is  16,  but  the  third  (K-Rb)  is 
46  and  the  fourth  (Rb-Cs)  is  47. 

With  the  increase  of  atomic  weight  he  holds  that 
volume  and  density  also  increase.  Further,  the  atom  is 
supposed  to  be  made  up  of  certain  units  of  matter  and  it 
is  maintained  that  the  increase  of  density,  with  increase 
of  atomic  weight,  shows  that  so  long  as  the  total  volume 
of  the  atom  increases,  the  volume  of  each  unit  of  matter 
which  enters  into  its  composition  diminishes.  The 
action,  or  the  mutual  attraction  of  the  particles  results  in 
drawing  them  nearer,  and  this  makes  the  volume  of  each 
unit  diminish  in  spite  of  the  increase  of  the  total  volume. 

This  diminution  of  the  volume  of  an  atom  is  called 
the  “loss”  ( la perte .)  By  mathematical  reasoning,  ap- 
plied especially  to  the  group  of  the  alkalies,  since  “ the 
numerical  coincidences  can  not  be  chance”  two  laws 
are  deduced  : 

1.  The  losses  are  proportional  to  the  masses. 

2.  They  are  inversely  proportional  to  whatever  it  may 
be  required  to  determine. 

' The  first  is  called  the  law  of  proportionality  of  the 
losses ; the  second  is  the  law  of  the  diminution  of  the  losses. 

This  law  can  be  formulated  as  follows  : 

Pi  Pi  y 

m3 


m 


tchitcherine’s  system. 


237 


The  last  term  is  a constant,  which  expresses  the  bond, 
or  the  reciprocal  action  of  each  unit  with  each  unit,  or, 
that  which  may  be  called  the  force  of  cohesion,  or 
molecular  attraction,  of  the  atom.  In  multiplying  this 
value  by  the  mass  m,  the  bond  of  each  unit,  with  all  the 
others,  is  gotten.  The  strength  of  this  bond  is  meas- 
ured by  the  drawing  together  of  the  particles,  that  is  to 
say,  by  the  diminution  of  their  volume,  or  the  loss. 
Henc ep=fm.  Under  these  conditions  the  volume  of 
each  unit  or  the  partial  volume,  as  it  may  be  called,  for 
brevity’s  sake,  is  expressed  by  the  formula  v=2—fm,  and 
the  total  volume  of  the  atom  will  be  V = vm  = fm~. 

If  we  compose  a table  on  this  basis  for  the  entire  series 
of  numbers,  commencing  with  the  unit,  taking  the  force 
of  cohesion  equal  to  that  of  lithium  and  of  sodium,  i.  e., 

— or  0.0428571,  we  will  have  the  proportional  sizes 

(amounts)  of  the  losses,  the  volumes,  and  lastly  of  the 
densities.  In  this  table,  the  loss  will  increase  in  an 
arithmetical  progression,  with  a differential  equal  to 
0.0428571,  and  the  partial  volume  will  diminish  in  the 
same  dimension  until  the  first  decrease  is  equal  to  the 
second  and  the  second  to  zero.  The  last  term  of  the 
progression  will  be  given  consequently  by  the  equation 
2 

2 —fm—  o,  or  m If  f—  0.0428571,  the  last  term 

of  the  progression  will  be  46-f,  a very  remarkable  num- 
ber in  the  system  of  the  chemical  elements,  since  it  is 
equal  to  a great  period,  that  is,  the  distance  between 
potassium  and  rubidium,  etc. 


238 


THE  PERIODIC  LAW. 


Further,  Tchitcherine  discusses  the  nature  of  the  atoms. 
The  periphery  of  an  atom  is  taken  to  be  the  exterior 
limit  of  the  matter  contained  in  it — the  surface  of  a 
sphere,  a ring,  or  simply  the  orbit  of  a body  revolving 
around  the  central  mass.  The  correspondence  of  the 
central  mass  to  that  of  the  periphery  has  its  bearing 
then  upon  the  observed  facts  andlaws.  This  idea  is  illus- 
trated by  the  relation  and  interaction  of  the  earth,  a 
central  mass  and  the  moon,  a peripheric  mass. 

All  of  the  chemical  elements  take  the  form  of  a com- 
plete and  rational  system  following  and  determined  by 

771X 

one  single  formula  kp  — . Here  k is  a coefficient 

which  must  be  determined, ^designates  the  total  mass, i.e., 
atomic  weight,  jt  the  central  mass,  z that  of  the  periphery. 
Experiments  give  us  for  each  atom  the  value  of  p — fm. 
Of  these  two  factors  m indicates  the  proportio  nalvalue 
of  the  mass  and  ./the  relation  of  the  center  to  the  peri- 
phery. In  accordance  with  this  the  formula  becomes 

kf——.  If  m = x -(-  z,  the  two  unknowns  are  determined 
2 

by  it,  but  if,  besides  the  central  mass  and  the  periphery, 
there  is  a neutral  zone  and  m — x ~\-y  -(-  z,  then  it  is 
necessary  to  know  either  x or  z. 

In  the  alkali  group  lithium  is  taken  as  the  central 
mass.  The  calculation  gives  for  Na  : x = 7,  z = 16  ; for 
K : x—  7,  z=t,2  ; for  Rb  : x=  j,  y = 32,  z = 46  ; for 
Cs  : x = 7,  y — 64,  z—  62. 

The  atoms  appear  as  analogues  of  the  solar  system, 
with  a central  mass  and  bodies  revolving  around  it. 


SUTHERLAND’S  NEW  PERIODIC  PROPERTY.  239 


155.  Sutherland’s  New  Periodic  Property  of  the  Ele- 
ments (194). — In  solids,  the  molecules  may  be  as- 
sumed to  vibrate  about  a mean  position,  and,  at  some 
characteristic  temperature,  each  solid  may  be  said  to 
have  a period  of  vibration  characteristic  of  its  molecule. 
The  most  likely  temperature  for  which  this  would  be  the 
case  would  be  the  melting  point,  when  the  vibratory 
motion  of  the  molecule  just  breaks  down.  Suppose  a 
molecule  of  mass  M and  mean  specific  heat  C,  heated 
up  from  rest  at  absolute  zero  to  its  melting  point  T.  It 
receives  heat  MCT  proportional  to  its  kinetic  energy 
\Mv\  where  v is  the  velocity  of  the  molecule  at  the  melt- 
ing point.  By  Dulong  and  Petit’s  law,  MC  is  approxi- 
mately constant  for  the  elements,  so  that  v is  proportional 


ume  occupied  by  the  molecule  : and  if  a is  the  mean 
coefficient  of  linear  expansion  of  the  substance  between 


crease  in  the  linear  dimensions  of  the  space  occupied  by 
a molecule  when  heated  from  zero  to  T , and  therefore 
represents  the  length,  or  amplitude,  of  the  vibration 
just  as  it  is  going  to  leave  the  vibratory  state  charac- 
teristic of  the  solid.  Hence  the  periodic  time  p of 
the  molecule  at  the  melting  point  is  proportional  to 


Knowing  thus  the  velocity  of  vibration  from  its 

length  L,its  time,  or  period  is  obtainable.  Let  d be 

M 

the  density  of  the  substance,  then — represents  the  vol- 


240 


THE  PERIODIC  LAW. 


a T ( Md y5  -y/  - . The  value  of  a is  unknown  for  any 

elements,  but  the  author  has  found  an  empirical  equation 
by  means  of  which  it  may  be  determined,  namely,  aTM * 
= const.,  the  constant  being  about  0.045  for  all  metals 
except  antimony,  bismuth  and  tin.  Substituting  this 
value  and  dropping  all  constants  from  the  formula,  p 


becomes 


proportional  to  . 


Taking  M as  the 


atomic  weight,  and  calculating  the  period  of  vibration 
by  the  above  formula,  we  get  for  the  lithium  family:  Li, 
0.21  ; Na,  0.43  ; K,  0.66  ; Rb,  0.96  ; Cs,  1.23  ; or  num- 
bers in  the  ratio  1,  2,  3,  4,  5,  6,  and  for  the  next  group, 
Be,  0.35  ; Mg,  0.70  ; Ca,  1.04  ; Sr,  1.62  ; Ba,  1.88  ; or 
numbers  in  the  ratio  1,  2,  3,  4,  5,  and  5.3.  Copper  and 
silver  have  periods  0.21  and  0.30,  which  are  nearly  as  2 
to  3,  and  involve  the  same  fundamental  constant  as  the 
main  family  ; and  zinc  and  cadmium  have  periods  0.32 
and  0.47,  in  which  the  same  peculiarity  occurs.  The 
periods  of  other  elements  do  not  exhibit  such  a marked 
relation,  but  the  following  series  is  remarkable : Mn,  0.16; 
Fe,  0.16;  Co,  0.16;  Ni,  o.  17,  Ru,  0.21  ; Rh,  0.20  ; Pd, 
0.23  ; Os,  0.23;  Ir,  0.25;  Pt,  0.27. 

The  periods  of  vibration  of  compounds  are  also  consid- 
ered, and  it  is  found  that  p for  each  molecule  is  a sum 
of  parts  due  to  each  atom  in  the  molecule. 

156.  Carnelley’s  Algebraic  Expression  of  the  Periodic 
Law  (195).  The  atomic  weights  of  the  elements, 
arranged  according  to  the  periodic  law,  may  be  repre- 
sented by  the  formula  A = c (m  -f-  vx)  where  A is  the 


carnelley’s  algebraic  expression. 


241 


atomic  weight,  c is  a constant,  m a member  of  an  arith- 
metical progression,  depending  on  the  series  to  which 
the  element  belongs,  and  v the  maximum  valency  of 
the  group  of  which  the  element  is  a member.  After 
numerous  trials,  the  best  results  have  been  obtained 
when  * = 2 and  m = 0,2^,  5,  5 + 3v>  5 + 2 (3$),  5 + 3 
(3^),  etc.,  for  each  series  respectively,  from  series  II  to 
XII  of  Mendeleeff’s  table,  so  that  m is  a member  of  an 
arithmetical  progression  in  which  the  common  difference 
is  3^-,  except  in  the  first  two  terms,  where  the  common 
difference  is  2\. 

The  calculated  values  for  c vary  from  6.0  (carbon)  to 
7.2  (selenium)  with  a mean  value  of  6.64.  The  high 
values  of  c occur  mainly  with  elements  belonging  to  the 
higher  groups  (namely,  V,  VI,  and  VII)  whilst  low 
values  belong  to  the  lowrer  groups  (I,  II,  and  III.)  The 
greatest  extremes  occur  in  group  IV,  Ti  and  Ge  being 

high,  C and  Si  low.  The  equation  A = c (m  +-y+)  be- 
comes A — c{m  +1)  for  elements  of  the  first  group,  so 
that  for  potassium  c(w4+  1)  =39  and  for  silver 
c ( m 7 + 1 ) = 107.7.  If  x represents  the  common  differ- 
ence in  the  arithmetical  progression,  then  m 7 = m*  -(-  x, 
and  + 1)  + 3x0=  39-f-  3^  from  which  xr 

= 22.90.  In  the  same  way,  by  taking  different  pairs 
of  elements  of  group  I,  different  values  for  xc  are  obtained, 
the  mean  of  which  is  22.85,  or  “ the  difference  between 
the  atomic  weights  of  any  two  elements  ingroup  I (from 
series  IV  upwards) , divided  by  the  difference  between 
the  number  of  series  to  which  each  element  belongs 


242 


THE  PERIODIC  LAW. 


gives  a constant,  or — — — = const.  = 22.85  where  x 

y x 

and  y are  the  numbers  of  the  series  to  which  the  ele- 
ments A and  B respectively  belong.”  The  constant 
22.85  is  very  nearly  identical  with  the  atomic  weight  of 
sodium  (22.99).  Atomic  weights  calculated  from  the 

equation  A — c (m  -j-^j  v)  agree  more  closely  with  the 

observed  values  than  do  those  determined  by  Dulong 
and  Petit’s  law.  Specific  volumes  calculated  from  the 
volumes  so  obtained  agree  well  with  the  usual  values. 
The  greatest  discrepancies  occur  at  the  end  of  series 
IV,  V,  and  VII,  and  at  the  begining  of  series  XI. 

In  the  equation  A = c {m  -f  yj  v),  the  constant  c has 

a mean  value  of  6.6,  which  suggests  the  constant  6.4  of 
Dulong  and  Petit’s  law.  If  c represents  the  atomic  heat, 

then  atomic  weight  = atomic  heat  X ( m +-^T)  = atomic 


weight  X specific  heat  X ( m v),  or  1=  specific 


heat  X whence  specific  heat 


Spe- 


m-\-  v' v ' 

cific  heats,  calculated  in  this  way,  agree  closely  with  the 
observed  values,  especially  if  specific  heats  at  high 
temperatures  be  taken,  since  in  this  case  the  constant 
6.4  of- Dulong  and  Petit’s  lawT  approximates  to  6.6. 


The  value  m in  the  equation  A — c (m  -)-  ^ ! v)  is  the 


member  of  an  arithmetical  progression,  and  is  a whole 
number  for  the  even  series  and  a number  and  a half  for 


EVOLUTION  OF  THE  ELEMENTS.  243 

the  odd  series,  in  this  way  b corresponding  with  the 
well-known  difference  between  the  series.  Again,  the 
common  difference  is  for  the  first  three  members,  but 
is  3^  afterwards.  This  accords  with  Mendeleeff’s  state- 
ment, that  the  second  and  third  series  are  more  or  less 
exceptional. 

157.  Wendt  on  the  Evolution  of  the  Elements. — 

(201).  The  natural  system  of  the  elements  is  looked 
upon  as  giving,  as  the  first  periodicity,  seven  rows  of 
three  elements  each,  as  for  instance  Li,  Na,  and  K, 
which  bear  the  closest  relationship  to  one  another.  This 
is  adduced  as  a parallelism  to  the  three  physical  states  of 
matter,  and,  through  analogy,  as  an  argument  for  the 
evolution  of  the  elements.  It  is  not  to  be  looked  upon 
as  purely  molecular  nor  atomic,  but  as  a change  of  physi- 
cal state  on  the  part  of  like  atoms,  in  accord  with  the 
laws  for  changes  of  the  state  of  molecules.  These 
changes  of  state  belong  not  merely  to  the  first,  called  by 
the  author,  stem-elements,  but  the  first  3X7  elements 
have  the  same  capacity  for  change.  Therefore  the  law 
runs  thus  ; out  of  the  seven  stem-elements  two  rows  of 
seven  elements  each  were  gradually  evolved  and  fur- 
ther from  each  of  the  3X7  elements  another  row 
sprang. 


lie 

IIIc 

1 

/ 

lb 

lib 

III6  III6 

1 

/ 

\ / 

la 

lla 

Ilia 

/I  / / 

Ic  I II III 

The  elements  are  arranged  into  various  groups  and  num- 


244 


THE  PERIODIC  LAW. 


bered  accordingto  the  order  of  their  evolution  I,  II,  III, 
la,  Ila,  Ilia,  etc.  The  reasons  for  thus  arranging  certain 
of  the  elements,  as  H,  Cr,  etc.  are  discussed  at  length. 
There  are,  as  may  be  seen  by  reference  to  the  table, 
many  variations  from  the  table  of  Mendeleeff.  Further- 
more this  system  does  not  show  rows  of  unknown  ele- 
ments. It  shows  at  the  most  n X 7 -+-  2 = 79,  at  the 
least  74,  or  a mean  of  77. 

The  claims  made  are,  that  the  law  on  which  the  scheme 
is  based  is  the  only  possible  explanation  for  the  connec- 
tion between  the  groups  and  the  series  of  elements. 
Again,  that  by  it  the  so-called  double  periodicity  and  also 
the  connection  between  the  various  parts  of  the  groups 
are  explained.  Thirdly  the  iron,  platinum  and  cerium 
groups  find  their  positions  and  explanations.  In  the 
fourth  place  the  Kant-Laplace  nebular  hypothesis,  so 
generally  accepted,  demands  the  evolution  of  the  solar 
system.  The  astro-physics  shows  the  evolution  of  the 
celestial  bodies  and  at  the  same  time  of  the  elements  by 
the  gradual  aggregation  or  growth  of  the  same— undoubt- 
edly after  their  introduction. 

The  existence  of  three  elements  on  some  celestial 
bodies  and  of  eighty  on  others,  according  to  density, 
would  be  without  explanation  were  not  the  elements  the 
result  of  evolution.  The  periodicity  of  the  maxima  and 
minima  of  the  sun-spots,  in  connection  with  the  appear- 
ance of  the  spots  in  distinct  localities  only,  and  the 
difference  of  the  prominences,  seem  to  point  to  a contin- 
ual formation  of  elements.  The  presence  of  the  gas  D , 
less  dense  than  hydrogen,  upon  the  sun  seems  to  mean 


3 

B 
2 
O 
H 
t n 


Q 

B 

S! 

B 

B 

> 

g 

O 

B 

B 

B 

O 

B 

t-J 

K 

B 


r 

B 


g 


C/5 


246 


THE  PERIODIC  LAW. 


that  in  the  cooling  of  the  earth  such  a gas  would  be  con- 
densed and  hence  could  not  exist  upon  it. 

Evolution  can  not  be  restricted  to  organic  life  since 
chemistry  has  shown  that  the  special  power  or  energy 
called  vital  force  does  not  exist.  With  regard  to  the 
formation  of  the  seven  fundamental  elements  the  author 
seems  most  inclined  to  adopt  the  views  of  Griinwald. 
At  any  rate  they  are  composed  of  primal  matter.  The 
benefits  to  be  derived  from  the  table  he  sets  forth  under 
thirteen  different  headings. 

His  diagram,  illustrating  his  ideas  as  to  the  relation- 
ship and  generation  of  the  elements,  may  be  examined 
and  the  similarity  of  his  conceptions  to  Preyer  and  others 
will  be  seen. 

158.  A Tabular  Expression  of  the  Periodic  Relations 
by  Bassett.  — The  author  first  (202)  mentions  some 
anomalies  in  the  table  of  Mendeleeff,  as  for  instance, 
‘ ‘ the  great  blank  space  in  the  fifth  column  with  no  in- 
dication of  the  existence  of  any  metals  between  silver 
and  gold  downwards.  Again  Yb,  one  of  the  least  basic 
earths,  follows  La  the  most  powerfully  basic  of  all. 
Also  Di,  with  strongly  basic  oxide,  separates  Nb  and 
Ta,  etc.” 

The  arrangement  which  he  suggests,  as  meeting  these 
difficulties,  “ simply  amounts  to  an  alteration  in  the 
position  of  Mendeleeff’ s ninth  group  and  the  addition  of 
one  interperiodic  group.”  The  author  describes  his 
table  as  follows : 

“ If  wre  cut  a strip  of  paper  on  wffiich  the  table  has 
been  written  and  roll  it  round  a cylinder  whose  circum- 


Bassett’s  Tabee. 


Cs  133  226  ? 

Ba  137  ? 

La  138.2  ? 

Ce  140.2  Th  232.6 
Ndyi4o.8  ? 
Pdy  143.6  U 239.6 
148  ? 241  ? 


Sm 

150 

? 

? 

? 

? 

? 

154  ? 

248  ? 

? 

? 

Tb 

159-5 

? 

Ho 

162 

? 

? 

? 

Er 

166.3 

? 

169  ? 

263  ? 

Tm  170.4 
? 


Yb  173 


K 

39-1 

Rb 

85-5 

174  ? 

Ca 

40 

Sr 

87.6 

? 

Sc 

44 

Y 

89.1 

? 

Ti 

48 

Zr 

90.6 

? 

V 

51.4 

Nb 

94 

Ta 

182.6 

Cr 

52.1 

Mo 

96 

W 

184 

Mn 

55 

100  ? 

. 189  ? 

Fe 

56 

Ru 

101.6 

Os 

I9I-7 

Ni 

58.7 

Rh 

103-5 

Ir 

I93-1 

Co 

59 

Pd 

106.6 

PC 

195 

Li 

7 

Na 

23 

Cu 

63-4 

Ag 

107.9 

An 

197-3 

Be 

9 

Mg 

24-3 

Zn 

65-3 

Cd 

1 1 2 

Hg 

200 

B 

II 

A1 

27 

Ga 

69 

In 

113-7 

Tl 

204.2 

C 

12 

Si 

28.4 

Ge 

72.3 

Sn 

119 

Pb 

207 

N 

14 

p 

3i 

As 

75 

Sb 

120 

Bi 

208.9 

0 

l6 

•s 

32-i 

Se 

79 

Te 

125 

? 

F 

19 

Cl 

35-5 

Br 

SO 

I 

126.9 

216  ? 

(To  face  p.  246.) 


PERIODIC  RELATIONS  BY  BASSETT.  247 

ference  is  equal  to  ten  of  the  vertical  spaces,  beginning 
at  the  bottom,  we  produce  a series  of  derived  tables  of 
considerable  interest.  The  first  of  these  is  simply  the 
lowest  portion  of  the  primary  table  as  it  stands.  It  will  be 
seen  that  the  elements  in  the  three  lower  lines  show 
very  complete  analogies,  and  a regular  gradation  in 
properties  from  left  to  right,  while  in  the  four  upper 
lines  this  is  by  no  means  so  clearly  perceived. 

“The  second  fold  of  the  paper  round  the  cylinder  covers 
up  all  but  the  two  left-hand  small  periods  and  gives  rise 
to  the  following  : 


Li 

Na 

K 

Rb 

? 

Be 

Mg 

Ca 

Sr 

? 

B 

A1 

Se 

Y 

? 

C 

Si 

Ti 

Zr 

? 

N 

P 

V 

Nb 

Ta 

0 

S 

Cr 

Mo 

W 

F 

Cl 

Mn 

? 

p 

“Na  is  removed  from  its  anomalous  place  by  Cu  ; Mg, 
A1  and  Si  also  find  more  congenial  neighbors,  and  so 
on.  By  a third  fold  of  the  paper  the  last  column  above 
is  covered  and  a new  one  containing  Tb,  Ho,  and  Hr  is 
produced.  The  last  fold  of  the  paper  covers  this  up 
and  gives  finally  the  column  Cs,  Ba,  La,  Ce,  etc.  and 
another  with  Th  and  Ur.  This  gives  alkalies,  etc.  com- 
plete and  is  derived  from  the  first  table  by  successive 
upward  shifts  of  the  first  and  second  pairs  of  groups  or 
periods.” 

The  author  emphasized  the  importance  of  the  atomic 
volumes  in  the  arrangement  of  the  periods,  though  the 
atomic  weights  are  regarded  as  of  prime  importance. 


248 


THE  PERIODIC  LAW. 


159.  Wilde  on  the  Origin  of  the  Elements. — The 

preface  to  this  paper  (203)  contains  a criticism  of  the 
system  of  Mendeleeff  with  especial  reference  to  the  idea 
of  periodicity.  “ From  the  numerous  discrepancies 
which  present  themselves  in  the  classification  of  the  ele- 
ments when  arranged  in  the  regular  order  of  their  atomic 
weights,  it  will  be  obvious  that  the  idea  of  recurring 
properties  or  periodic  functions,  in  terms  of  the  vertical 
series  of  Newlands  or  the  horizontal  series  of  Mendeleeff, 
has  no  more  relation  to  chemical  science  than  the  law  of 
the  increase  of  population,  or  the  laws  of  variation  and 
inheritance  in  organic  species.”  The  author  compares 
the  nebular  theory  and  its  condensations  with  supposed 
elementary  condensations,  giving  tables  of  numerical 
relations  among  the  planetary  distances  and  also  between 
the  atomic  weights.  He  gives  several  tables  in  illustra- 
tion of  this,  thus: 

Table  II. 

0 . o . 7 = Li  = 7 

1 X 23  — - o = Na  = 23 

2 X 23  — 7 = K =39 

3 X 23  — 7 = Cu  = 62 

4 X 23  — 7 = Rb  = 85 

5 X 23  — 7 = Ag  = 108 

6 X 23  — 7 = Cs  = 131 

7 X 23  — 7 = =154 

8 X 23  — 7 = =177 

9 X 23  — 7 = Hg  = 200 

A similar  table  is  given  for  the  Be  group  with  1 
(2,  3,  etc.)X  24 — 8 ; and  another  for  the  elements  C,  Al, 
Yt,  In,  E,  Tl,  and  Th.  with  1 (2,  3,  etc)  X 27 — 12. 


ORIGIN  OF  THE  ELEMENTS. 


249 


He  gives  as  further  relations  “ observable  between  in- 
ter-planetary voids  and  atomic  condensations 

1 . The  regular  geometric  series  of  the  planetary  dis- 
tances commences  at  the  second  member  ^of  the  system, 
and  the  regular  arithmetical  series  of  atomic  weights 
commences  at  the  second  and  corresponding  member  of 
each  series. 

2.  As  the  atomic  weight  of  the  second  element  in  each 
series  is  half  the  sum  of  the  atomic  weights  of  the  first 
and  third  elements,  so  is  the  distance  of  the  second  mem- 
ber of  the  solar  system  an  arithmetical  mean,  or  half  the 
sum  of  distances  of  the  first  and  third  members. 

3.  The  atomic  weight  of  the  fourth  member,  in  each 
series  of  elements,  is  equal  to  the  sum  of  the  atomic 
weights  of  the  second  and  third  and  the  distance  of  the 
fourth  member  of  the  solar  system  is  also  equal,  within 
a unit,  to  the  sum  of  the  distances  of  the  second  and 
third  members. 

4.  As  the  smallest  planetary  distance  is  a constant  func- 
tion of  the  distances  of  the  outer  planetary  bodies,  so  is 
the  least  atomic  weight  in  each  series  a similar  function 
of  all  the  higher  members  of  the  series  to  which  it  be- 
longs. 

Other  relations  are  pointed  out  but  enough  has  been 
given  to  show  their  nature.  Following  Prout,  he  as- 
sumed “ that  hydrogen  is  the  ponderable  base  of  all  ele- 
mentary species  and,  further,  that  it  is  probable  that 
this  element  itself,  as  further  maintained  by  Prout,  may 
have  been  evolved  from  an  ethereal  substance  of  much 
greater  tenuity.” 


250 


THE  PERIODIC  LAW. 


In  his  hypothesis  he  assumed,  (i)  that  a mass  of  hy- 
drogen of  a curvilinear  form,  acquired  a motion  of  rota- 
tion about  a central  point  which  caused  it  to  take  a 
spiral  or  convolute  form.  (2)  As  each  successive  spiral 
or  convolution  was  formed,  the  particles  of  hydrogen 
combined  with  themselves  as  far  as  the  septenary  com- 
bination, constitute  the  type  of  each  series  of  elements, 
the  number  of  types  or  series  being  equal  to  the  number 
of  convolutions  of  the  rotating  gas.  (3)  That  on  a 
further  condensation  of  the  elementary  matter  a transi- 
tion from  the  spiral  to  the  annular  form  occurred,  during 
which,  or  after  which,  the  series  under  each  type  was 
generated  in  concentric  zones,  and  in  the  order  of  their 
atomic  weights,  until  the  highest  member  of  each 
species  was  formed.  (4)  That  as  the  elementary 
vapors  began  to  condense  or  assume  the  liquid  form  their 
regular  stratification  would  be  disturbed  by  eruptions  of 
the  imprisoned  vapors  from  the  interior  of  the  restating 
mass.  This  disturbance  would  be  further  augmented 
by  the  subsequent  combination  of  the  negative  with  the 
positive  and  also  by  the  various  solubilities  of  their  newly 
formed  compounds. 

In  his  annexed  table  are  arranged  all  the  known  ele- 
ments in  natural  series,  wherein  gaps  appear,  as  in 
Tables  II.  and  III.,  which  indicate  the  existence  of 
missing  elements.  The  atomic  weights  of  other  elements 
which  have  not  been  sufficiently  investigated  are  also 
determined.  If  the  theory  of  the  evolution  of  elementary 
substances  from  hydrogen  be  correct,  the  numbers  re- 
presenting the  atomic  weights  also  represent  the  number 


NEW  NUMERICAL  RELATIONS  BY  ADKINS. 


251 


of  the  particles  of  hydrogen  from  which  the  elements 
were  formed. 

In  a later  paper  the  author  reiterates  his  views  as  to 
Prout’s  Hypothesis  and  vigorously  criticises  Mendeldeff 
and  the  idea  of  periodicity. 

160.  New  Numerical  Relations  by  Adkins. — Accord- 
ing to  this  paper  (207)  all  of  the  atomic  weights  can 
be  formed  from  those  of  the  first  four  elements  : Li,  7 ; Be, 
9;  B,  11  ; C,  12.  They  are  formed  in  regular  sequence  by 
taking  a “ basic  number”  which  is  either  an  alkali  or 
an  alkaline  earth  and  adding  a regular  sequence  of  the 
atomic  weights  : a small  anomalous  group  is  the  only  ex- 
ception, together  with  a duplication  of  12  in  magne- 
sium. 

Basic  number  7 7 7 7 Alkali  12 

Sequence  7 9 11  12  “ 12 


I4=N  16=0  (18)?  I9=F 

Basic  number  999 

Continued  sequence  14  16  18 


24=Mg 

9 

19 


23=Na  25?  27=A1  28=Si 

Anomalous  Group,  Alternate  Alkali  and  Earth  Base. 


24 

23 

24 

24 

24 

23 

24 

7 

9 

II 

12 

14 

16 

19 

3i=P 

t n 

II 

1 £ 

0 

II 

l 8 

36= Cl 

(38)? 

39=K 

(43)  ? 

Explanations  are  offered  of  the  position  of  Mg  and 
Na  ; Mg  is  made  up  of  two  elements  12  and  12  and  Na 
of  three,  7,  9,  and  7.  Chlorine  is  said  to  be  of  compound 

character,  35  + 36  = = 35.5. 


252 


•THE  PERIODIC  LAW. 


It  is  scarcely  necessary  to  give  more  of  the  sequences 
arranged  by  this  author.  Suffice  it  to  say  that  they  are 
more  strained  and  complicated  as  the  atomic  weights 
increase.  Finally,  he  says  “ the  remaining  groups  are 
so  incomplete  that  it  is  difficult  to  follow  further  on  this 
system  but  they  can  be  developed  in  another  way.” 
There  is  no  discussion  as  to  the  meaning  of  these  groups 
nor  of  their  chemical  relations,  nor  are  any  reasons  given 
for  the  assumption  of  ‘‘basic  numbers”  and  of  sequences, 

. and  the  reader  is  unfortunately  left  in  the  dark  as  to  the 
object  of  the  entire  calculation. 

161.  fleusel  on  the  Oneness  of  the  Elements. — 
Meusel  (208)  sought  to  find  in  the  differences  between 
the  atomic  weights  of  the  members  of  the  different  series 
a revelation  of  the  composition  of  the  elements.  These 
point  to  a common  factor.  One  cannot  longer  think  of 
the  chemical  elements  as  simple  bodies,  still  it  is  diffi- 
cult to  deduce  this  common  factor.  The  best  method 
seemed  to  the  author  to  be  to  take  the  differences  of  the 
first  members  of  the  different  series,  that  is,  Li,  Be,  B,  C, 
N,  O,  and  F. 

Li  7-oi  = 3-99  + 3-°2 

Be  9.08  = 3(3.02)+  0.02 

B 10.09  = 2 (3.99)  + 3.02 

C ri.97  = 3 (3-99) 

N 14.01  = 2 (3.99)  + 2 (3.02)  — 0.01 
O 15.96  = 4 (3.99) 

F 19.06  = 3.99  + 5 (3.02)  — 0.03 

A table  is  given  showing  that  all  the  atomic  weights 
can  be  built  up  out  of  these  two  factors,  3.99  and  3.02 


ONENESS  OF  THE  ELEMENTS. 


253 


with  small  plus  and  minus  differences.  These  differences 
are  regarded  rather  as  giving  proof  that  the  elements  are 
made  up  of  these  two  factors,  than  otherwise,  since  the 
atomic  weights  are  not  accurately  known  and  absolute 
accord  is  not  to  be  expected.  That  one  of  the  elements, 
hydrogen,  has  an  atomic  weight  less  than  either  of  the 
factors  may  be  explained  on  the  ground  that  all  of  them 
have  like  origin,  or  consisting  of  like  primal  matter 
and  show  similarity  of  constitution. 

“ The  next  task  was  to  discover  the  common  origin 
of  the  three  magnitudes  1.00,  3.99,  and  3.02  and  if  pos- 
sible to  get  a clear  idea  of  the  space  relations  of  these 
weight  magnitudes.  For  the  solution  of  the  problem 
the  simplest  system  was  adopted  in  accord  with  moving 
atoms.  The  simplest  forms  in  space  determined  by  four 
given  points  are  the  tetrahedron  and  the  sphere.  The  four 
angles  of  a tetrahedron  replaced  by  four  atoms  form  the 
simplest  system  reconcilable  with  the  movement  of  the 
atoms.  This  tetrahedron  is  taken  as  the  starting  point. 
An  increase  of  this  tetrahedron  by  a similar  one  would 
give  seven  points  and  upon  forms  in  space  of  four  and 
seven  points  the  following  combination  forms  can  be 

gotten : 10. . 13. . . . 100 133 199.  . . 202 

334,  etc.  If  these  points  represent  atoms  of  primal  matter 
we  will  have  bodies  formed  by  tetrahedral  series  of  pri- 
mal matter. 

“But  we  can  not  stop  with  this  representation.  Series 
in  right  lines  would  have  no  limit  and  lead  to  endless 
forms  and  this  would  conflict  with  our  present  knowledge 
of  matter.  Considerations  of  gravity  and  motion  make 


254 


THE  PERIODIC  EAW. 


circular  series  of  the  spherical  form  more  probable. 

“ If  thirty-three  tetrahedra  are  arranged,  with  one 
common  point  for  each  pair,  in  a half  circle,  one  end 
will  be  formed  by  the  figure  -f-  f-  and  the  other  by  — 
The  final  tetrahedron  corresponds  to  the  first,  turned 
through  i8o°.  The  simplest  system  of  such  uniformly 
moving  bodies,  consisting  of  ioo  atoms,  would  be  two  such 
half  circles.  Thus  each  half  circle  would  be  an  atom  of 
hydrogen,  and  the  complete  circle  a molecule.  A larger 
molecule  of  this  body  has  never  been  observed  and  the 
creative  thought  has  used  this  for  building  all  the  so- 
called  chemical  elements. 

“ Let  us  test  this  supposition  upon  the  magnitudes 
3.99  and  3.02.  In  condensing  two  half  circles  of  atoms 
of  hydrogen,  one  atom  of  the  primal  matter  forms  the 
point  of  union,  thus  the  two  wrill  consist  of  199  such 
atoms.”  To  get  this  number,  3.99,  the  author  unites  two 
such  figures,  1.99,  plus  a binding  atom,  and,  for  the 
magnitude,  3.02,  it  is  one  figure  1.99  and  one  half  circle 
bound  together  by  four  atoms. 

‘‘The  space  relations  of  these  magnitudes  can  be  fixed 
by  the  specific  gravity,  or  atomic  volume,  of  the  chemi- 
cal elements.  Each  of  these  magnitudes  has  two  sizes. 
For  3.99  we  see  in  carbon  the  size  1.2  with  sp.  gr.  3.324, 
while  in  lithium  the  size  is  6.76  with  a sp.  gr.  0.5902. 
The  magnitude  3.02  corresponds  in  ber}dlium  to  the 
size  1.63  with  a sp.  gr.  of  1.853,  whilst  in  lithium  they 
are  5.12  and  0.5898,  respectively.” 

On  applying  this  theory  to  the  constitution  of  the 
various  elements,  the  author  thought  that  it  offered  an 


preyer ’s  genetic  system. 


255 


explanation  of  the  allotropism  of  certain  of  the  elements, 
this  being  due  to  molecular  rearrangement.  As  can  be 
easily  seen  the  elements  of  larger  atomic  weight  give 
wide  choice  as  to  constitution.  Thus  Cd,  111.7  or 
28(3.99)— 0-02  ;or37(3. 02)— 0.04;  or22(3. 99) + 8(3.02) 
—0.24;  or  25(3.99) +4(3.02)— 0.13. 

This  theory  is  further  considered  in  connection  with 
atomic  volumes  and  valence.  The  author  regards  the 
building  up  of  the  elements  as  a building  of  tetrogen 
(3.99)  and  trigen  (3.02),  in  accord  with  the  laws  of 
equilibrium.  This  same  principle  is  the  foundation  of 
chemical  combination  and  of  valence.  He  does  not 
believe  in  a specific  force,  chemical  energy.  Valence 
depends  upon  neither  atomic  volume  nor  upon  atomic 
weight ; it  is  ordered  neither  in  accordance  with  the 
metallic,  nor  the  non-metallic  character  ; it  is  not  sub- 
ject to  the  same  graded  changes  as  the  other  properties. 
Take  chlorine,  as  an  example.  Towards  electropositive 
hydrogen  the  atom  particles  of  chlorine  so  move  them- 
selves that  only  one  circle  has  need  of  a new  equilibrium. 
Some  elements,  however,  as,  for  instance,  the  electro- 
positive oxygen,  are  capable  of  so  influencing  the  motion 
of  the  atom-particles  of  chlorine  that  these  seek  a new 
equilibrium. 

Meusel  laid  special  stress  upon  the  proof  brought  to 
his  theory  by  thermo-chemical  data,  believing  that  his 
theory  alone  gives  these  their  proper  explanation. 

162.  The  Genetic  System  of  the  Elements  by  Preyer. 
— A table  is  given  by  Preyer  (206)  of  the  elements  ar- 
ranged in  fourteen  grades  or  steps.  These  steps  are 


256 


THE  PERIODIC  LAW. 


named  by  “step-numbers,”  from  one  to  fourteen,  giving 
thus  the  order  of  the  evolution  of  the  elements. 

1 

3 

6 4 

9 7 

14  11  12 

period  of  three  ; 5 is  the  fourth  seven  ; 6 is  the  fifth 
seven ; 7 is  the  second  period  of  three  ; 8 is  the  sixth 
seven  ; 9 is  the  seventh  seven  ; 10  is  the  eighth  seven  ; 
11  is  the  ninth  seven  ; 12  is  the  third  period  of  three ; 
13  is  the  tenth  seven  ; 14  is  the  eleventh  seven. 

These  correspond  to  five  generations  : 

1 

2 2 

323 

4 3 4 

5 4 4 4 5 

These  are  condensation  steps.  Thus  the  second 
condensation  would  give  rise  to  the  elements  of  steps  2, 
3,  and  4,  and  the  fourth  to  those  of  9,  11,  12,  10,  and  8, 
etc.  It  can  be  presumed  that  the  elements  of  steps  14 
were  formed  by  condensation  from  elements  9 and  both 
elements  9 and  1 r by  condensation  from  6 etc. 

Combining  the  five  generations  with  the  fourteen 
condensation  grades  the  following  stem-table  or  genetic 
system  is  derived. 

Three  of  the  eight  groups  will  be  here  given  as  illus- 
trating the  whole. 


2 

5 

8 

10  13 


preyer’s  genetic  system. 


257 


Rb  Cu 
! Ag 


H 

Li 

K Na 


H 

Be 

Ca  Mg 
Sr  Fe  Zn 


Y 


Sc  A1 


H 

Bo 


Ga 


Cs 


Dp  Srn  t 
odd  valence 


Sm  Au 


Ba  Ru  Cd  La 
Yb  Os  Hg 


Gd  T1 
odd  valence 


In 


even  valence 


And  so  other  groups  are  given,  springing  from  C,  N,  0, 
and  F. 

Here  we  find  the  various  families  recognized  and  in- 
cluded by  Mendeleeff  in  his  natural  system.  Here, 
however,  they  are  brought  into  their  genetic  relation- 
ship. Preyer  uses  a Roman  numeral  to  indicate  the 
generation  of  the  element  and  the  common  numeral  for 
the  condensation  step.  The  two  together  will  fix  the 
position  of  any  element.  Elements  belonging  to  the 
same  condensation  step  are  called  the  isotopic  elements  ; 
those  of  the  same  generation  are  said  to  be  stem-related. 

Proofs  for  the  correctness  and  truth  of  this  arrange- 
ment are  drawn  first  from  the  regularities  observed  in 
the  differences  between  the  atomic  weights.  A full  table 
of  the  differences  between  the  atomic  weights  of  stem- 
related  and  isotopic  elements  is  given.  First  we  have 
the  differences  between  the  first  and  second  generation. 
This  is  then  divided  by  the  difference  between  the  genera- 
tion numbers. 


2 — 1 = 1 

I.  Na  — Li  = iXi6.o 
II.  Mg  — Be  = 1X15.3 


3—  1 = 2 
K — Li  = 2 X 16.05 
Ca  — Be  = 2X  15.5 


4—  1 = 3 

II.  Fe  — Be  = 3X15.66 
IV.  Co—  C = 3X  15.3 
VI.  Ni — - 0=3X143 


25B 


THE  PERIODIC  LAW. 


These  differences  are  determined  for  all  generations. 
They  range  from  13.5  to  19. 1.  The  means  of  any  one 
series  range  from  14.88  to  18.75.  These  facts  are  sum- 
med up  into  a so-called  “ Law.” 

If,  instead  of  dividing  the  differences  between  the 
atomic  weights  by  the  differences  between  the  gradation 
numbers,  the  atomic  weights  themselves  be  divided,  the 
quotients  given  show  how  much  the  condensation  is 
from  the  beginning  in  the  various  gradations.  These 
quotients  range  from  11.52  to  17.3.  This  he  regards  as 
a new  means  of  controlling  doubtful  atomic  weights  and 
of  the  approximate  determination  of  those  of  unknown 
elements. 

Finally,  it  is  observed  that  the  arithmetic  mean  of  the 
atomic  weights  of  each  of  the  fourteen  series  of  isotopic 
elements  is  without  exception  the  same  as  the  atomic 
weight  of  the  elements  in  the  middle  column.  Thus  : 

Li  + Be+B  + C-f  N + O+F  = i2  j9  = c + c 5 

Na  + Mg  + Al  + Si  + P + S + Cl_^  :;_gi+n  r 

7 

The  specific  gravities,  atomic  volumes,  specific  heats, 
atomic  heats,  valence,  electro-chemical,  and  other  proper- 
ties are  all  tabulated,  and  the  numerical  relationships 
between  these  are  adduced  as  evidence  in  favor  of  this 
attempt  at  a genesis  of  the  elements. 

163.  Wislicenus  on  the  Nature  of  Matter.— Wisli- 
cenus,(209)  has  given  an  historical  review  of  the  develop- 
ment of  the  atomistic  idea  and  theories.  No  new  theories 
are  advanced.  The  Proutian  hypothesis  is  looked  upon 


NEW  PERIODIC  TABLE  BY  DEEEEY. 


259 


as  fully  disproved.  “Whatever  theory  as  to  the  nature  of 
matter  may  be  finally  accepted  it  must  be  based  upon 
chemical  and  physical  research  and  must  be  atomistic  in 
nature.’’ 

164.  A New  Periodic  Table  by  Deeley. — Deeley  (212) 
criticizes  some  points  in  the  table  of  Mendeleeff,  especi- 
ally his  arrangement  of  the  ‘ ‘typical  elements’  ’ or  as  some 
have  called  them  the  “ anomalous  elements.”  Mende- 
leeff seems  to  have  arranged  them  largely  for  symmetry, 
in  the  author’s  opinion.  He  objects  to  Meyer’s  diagram 
where  the  abscissae  are  atomic  weights  and  the  ordinates 
are  atomic  volumes,  because,  though  the  regular  variation 
of  the  ordinates  is  very  striking,  the  lines  joining  their 
summits  do  not  form  very  regular  curves.  This  might 
result  from  inexact  data  or  more  probably  from  lack  of 
corrections  for  temperatures  as  compared  with  melting 
points. 

His  diagram  is  constructed  in  much  the  same  manner 
as  L.  Meyer’s,  but  the  periodic  variations  of  some  other 
physical  constants  of  the  elements,  that  are  marked  by 
even  greater  regularity  than  are  the  atomic  volumes,  are 
plotted  upon  it.  The  two  constants  used  are  deduced 
from  the  atomic  weights,  the  relative  density,  and  the 
specific  heat.  These  constants  are  called  the  volume- 
heats  and  the  volume-atoms. 

The  volume-heats  are  the  quantities  of  heat  required 
to  raise  equal  volumes  of  the  elements,  in  the  solid  condi- 
tion, through  equal  temperatures,  whilst  the  volume- 
atoms  give  the  relative  numbers  of  atoms  in  equal 
volumes.  The  relative  density  changes  periodically  with 


Deeley’s  Arrangement— Classes  of  Oxides. 


Series  of  elements. 


(N  h<  M fOrj-iOVO  00  ON  O 


Distribution  iu  classes,  series  and  groups.  The  grouping  of  the  elements  is  indicated  by  arrows. 


palmer’s  views  of  the  elements. 


261 


increasing  atomic  weight.  The  specific  heat  does  not. 
Besides  increasing  rapidly  with  increasing  atomic  weight, 
the  relative  density  is  a markedly  periodic  value.  To 
illustrate  this  periodicity  the  regular  increase  of  density 
must  be  eliminated  from  the  ordinates.  This  is  accom- 
plished by  making  them  volume-atoms.  The  constants 
have  been  determined  for  the  elements  in  the  solid  state 
and,  when  allotropic  modifications  exist,  for  its  most 
stable  form.  The  following  equations  give  the  various 
relationships. 


,T  , . Relative  Densitv 

Volume-Atoms  =— : ; — j - . , 

Atomic  Weight 

Volume-Heats  = Relative  Density  X Specific  Heat. 

. . _ _ Volume-Heat 

Atomic  Heat  = 7 . 

Volume- Atoms 

In  the  diagram  given  by  Deeley,  the  abscissae  are  the 
atomic  weights,  and  the  ordinates  are  volume-heats  and 
volume-atoms.  The  volume-atoms,  to  enable  a clear 
comparison  to  be  made,  have  been  multiplied  by  6.1,  the 
mean  atomic  heat  of  Dulong  and  Petit.  Where  the  vol- 
ume-heats and  volume-atoms  are  almost  identical,  the 
spots  have  been  surrounded  by  circles. 

Diagram  1 includes  the  first  seven  elements  in  the  table 
of  Mendeleeff,  2 the  second  seven,  3 the  third  seven,  etc. 

With  the  exception  of  certain  peculiar  features,  which 
are  shown  by  the  elements  of  lower  atomic  weight  than 
aluminium,  the  elements  fall  naturally  into  eleven  series. 
Asecond  table  presents  these  more  completely  (page  260). 

i65.  Palmer’s  Views  as  to  the  Nature  of  the  Elements. 
— During  the  years  1890-1893  several  papers  were  pub- 


262 


THE  PERIODIC  LAW. 


lished  by  Palmer  (21 1)  bearing  upon  the  nature  of  the 
chemical  elements.  In  the  first  paper  attention  was  drawn 
to  the  facts  that  the  atomic  weights  are  the  chief  constants 
of  the  chemical  elements  ; that  they  follow  each  other 
in  a fairly  regular  progression  ; that  in  this  progression 
the  elements  beyond  hydrogen  arrange  themselves 
naturally  in  series ; that  the  natural  grouping  is  best 
shown  when  the  elements  are  arranged  in  series,  whether 
long  or  short,  which  begin  with  an  alkali  and  end  with 
a halogen  ; that  these  series,  either  long  or  short,  have 
a similar  progressive  variation  in  (a)  physical  properties 
(b)  chemical  properties,  and  (c)  in  chemico-physical 
properties.  From  these  facts  the  inference  was  drawn 
that  the  elements,  so-called,  are  made  up  of  two  sub-ele- 
ments or  ingredients,  viz. , kalidium  (Kd)  and  oxidium 
(Od). 

The  hypothesis  as  to  the  existence  of  these  sub-ele- 
ments is  then  examined  from  several  standpoints.  The 
elements  may  have  been  formed  by  the  addition  method 
as  Li  = Kd  ; Be  = Kd  -(-  Od  ; B = Kd  + Od,,  etc.  Or 
they  may  have  been  formed  by  the  substitution  method  : 
Li  = Kd„  ; Be  = Kd„  + Od  ; B = Kd4  + Od3  ; C = 
Kd,  -f-  Od3,  etc. 

The  addition  method  is  discarded  since  the  progres- 
sion is  not  a regular  one.  In  the  same  way,  considering 
the  simpler  substitution  method,  the  numerical  results 
are  by  no  means  satisfactory.  This,  he  says,  does  not 
dispose  of  the  question  of  the  composition  of  the  elements 
in  terms  of  oxidium  and  kalidium,  but  only  points  to 
another  mode,  and  probably  an  excessively  fine  degree 


palmer’s  views  of  the  elememts.  263 

of  subdivision  of  the  atom  in  terms  of  sub-atoms  ; i.  e. , 
that  the  atom  is  made  up  of  parts  excessively  minute  as 
compared  with  the  atom. 

The  hypothesis  that  hydrogen  is  the  proximate  in- 
gredient of  the  elements  is  discredited  because  the  atomic 
weights  have  not  been  found  to  be  exact  multiples  of 
unity  ; because  hydrogen  is  inherently  basic  and,  while 
it  might  be  looked  upon  as  the  prototype  of  basic-form- 
ing elements,  it  cannot  be  of  the  acid-forming  ; and 
lastly,  hydrogen  is  probably  part  of  a complete  independ- 
ent series  as  yet  unknown.  He  thinks  one  such  series 
possible  but  not  two.  The  supposed  properties  of  the 
last  element  of  this  series,  or  pre-fluorine,  are  discussed. 
As  to  the  generic  kalidium  and  oxidium,  he  states  that 
they  are  not  necessarily  concrete,  isolable,  varieties  of 
matter  but  they  represent  the  embodiment  of  those 
antithetic  properties  which  are  synonymous  respectively 
with  basiferous  and  acidiferous  properties.  This  is,  as 
he  points  out,  a return  to  the  Greek  idea  of  element  or 
principle.  An  hj^pothesis  as  to  the  genesis  or  evolution 
of  the  elements  is  then  advanced  as  an  explanation  of  the 
various  facts  observed  in  connection  with  the  atomic 
weights.  This  presents  an  analogy  to  the  nebular  hy- 
pothesis. The  various  theories  advanced  by  Palmer 
bear  many  points  of  resemblence  to  those  of  Zangerle, 
Crookes  and  other  writers  already  cited. 

The  author  criticizes  the  classification  of  Mendeleeff 
in  detail,  on  the  ground  of  the  forced  analogies  between 
certain  elements. 

He  gives  a new  arrangement  into  “short  and  long 


264 


THE  PERIODIC  LAW. 


series.”  His  theory  leads  him  to  the  supposition  that 
the  individual  atoms  of  the  same  element  may  differ 
among  themselves  as  the  blades  of  grass  on  the  lawn. 
To  settle  this  question  he  proposes  to  adopt  methods  of 
separation  like  fractionation.  This  we  have  seen  sug- 
gested by  Crookes  and  others  and  tried  by  Despretz. 
At  the  close  of  his  last  paper  he  said  that  a few  months 
would  see  much  light  thrown  upon  this  subject  by  the 
fractionation  of  silver  upon  which  he  proposed  to  start. 
Two  years  have  since  elapsed  without  further  report 
from  him. 

166.  Lothar  fleyeron  Teaching  Inorganic  Chemistry 
by  the  Aid  of  the  Periodic  System. — When  the  German 
Society,  according  to  its  custom  of  inviting  some  distin- 
guished specialist  to  lecture  before  it,  extended  its  invita- 
tion to  Lothar  Meyer,  he  devoted  (210)  the  opportunity 
him  to  an  earnest  argument  and  appeal  in  favor  of  afforded 
the  immediate  and  complete  introduction  of  the  periodic 
system  and  tables  into  the  regular  courses  of  instruction 
in  inorganic  chemistry.  He  pointed  out  the  necessity 
for  this  if  the  system  was  a true  one  and  the  great  sav- 
ing in  time  which  it  rendered  possible,  as  well  as  the 
clearness  of  order  and  treatment  gained.  It  means  to 
inorganic  chemistry  what  the  introduction  of  compound 
radicals  and  homologous  series  meant  to  organic  chem- 
istry and  will  accomplish  as  much  for  it. 

167.  Hinrichs  ontheTrue  Atomic  Weights. — Hinrichs 
has  reiterated  in  this  volume  (217)  his  ideas  about  the 
pantogen  atoms  and  the  composition  of  the  elements,  ex- 
pressed in  his  earlier  publications.  He  is  convinced 


HINRICHS  ON  THE  TRUE  ATOMIC  WEIGHTS.  265 

that  in  the  determination  of  the  atomic  weights  the 
analytical  ratios  found  depend  upon  the  amount  of  the 
element  used  in  the  experiment,  and  hence  that  there  is 
a systematic  variation  in  these  atomic  weights.  Some 
of  his  criticism  upon  the  methods  of  calculating  the 
atomic  weights,  at  present  in  vogue,  would  seem  to  be 
justified.  He  derives  what  he  styles  the  true  atomic 
weights  by  the  limit  method.  This  requires  the  “execu- 
tion of  a true  series  of  determinations,  all  made  under  ex- 
actly the  same  conditions,  with  exactly  the  same  ma- 
terials, and  differing  only  in  the  amount  of  the  inde- 
pendent taken,  and  this  amount  should  vary  grad- 
ually between  the  two  extremes  determined  by  the  possi- 
bility of  ready  handling  and  exact  determinations.’’ 

If  such  a series  is  plotted  over  the  atomic  weight  as  ab- 
sciss aand  the  analytical  ratio  as  ordinate,  the  latter  will 
determine  a parabolic  trajectory  which  has  its  convexity 
either  turned  up  or  down,  and,  accordingly,  exhibits 
either  a maximum  or  minimum. 

“ The  individual  values  determined  vary  according  to 
a definite  law,  approaching  a definite  limit  as  the  quantity 
of  matter  operated  upon  approaches  zero  ; and  that  this 
limit  gives  the  true  atomic  weights  on  which  chemical 
science  is  to  be  built.”  * 

The  standard  unit  taken  is  one  twelfth  of  the  atomic 
weight  of  carbon,  in  the  form  of  diamond.  Working  by  his 
limit  method,  he  regards  it  as  proved  “ that  of  nineteen 
elements  examined,  all  are  exact  multiples  of  the  hydro- 
gen weight.”  For  other  elements  new  determinations  are 
necessary.  In  a few  cases  these  weights  are  multiples 


266 


THE  PERIODIC  LAW. 


of  half  the  weight  of  hydrogen.  “ The  unity  of  matter 
is  the  logical  and  necessary  conclusion  from  this  fact.” 
168.  Rang’s  Periodic  Arrangement  of  the  Elements. 
— The  general  plan  of  Rang’s  table  (213)  is  to  arrange 
the  elements  in  their  respective  series,  so  that  all  the 
allied  elements  should  come  in  the  same  vertical  row. 

Rang’s  Periodic  Arrangement. 


Va- 

lence. 

1. 

II.  III. 

IV. 

V. 

VI. 

VII. 

VIII. 

2. 

Li 

Be  B 

C 

3- 

Na 

Mg  A1 

Si 

4- 

K 

Ca  Sc 

Ti 

V 

Cr 

Mn 

Fe  Ni 

Co 

5- 

Rb 

Sr  Y 

Zr 

Nb 

Mo 

Ru  Rh 

Pd 

6. 

Cs 

Ba  Di 

Ta 

W 

Os  Ir 

Pt 

7- 

Group 

Mn  -• 

2.  3- 

Th 

U 

. 

4- 

B. 

A. 

Va- 

lence. 

1. 

II. 

in. 

IV. 

V. 

VI. 

VII. 

I. 

H 

2. 

N 

O 

F 

3- 

. . 

P 

S 

Cl 

4- 

Cu 

Zn 

Ga 

Ge 

As 

Se 

Br 

5- 

Ag 

Cd 

In 

Sn 

Sb 

Te 

I 

6. 

Au 

Hg 

Tb 

Pb 

Bi 

Di  here  represents  all  the  triads  that  are  between  Ba  and  Ta. 
H may  not  be  exactly  in  its  true  place,  still  it  cannot  be  very 
far  from  it. 

The  table  has  been  divided  into  four  groups,  A,  B,  C, 
and  D,  where,  of  the  end  group,  A contains  the  strongest 


traube’s  system  of  the  elements.  267 

positive  elements,  and  the  other  end  group  D the  strong- 
est negative  elements.  In  the  center  groups  B are  the 
elements  with  high  melting  points  ; they  are  all  remark- 
able for  their  molecular  combinations.  At  one  side  of 
this  group  are  the  anhydro-combinations  : in  the  other 
center  group,  C,  are  the  heavy  metals  that  have  low 
melting  points.  If  groups  A and  D be  split  up  vertically 
in  respectively  three  and  two  parts,  the  table  presents 
seven  vertical  groups,  and  horizontally  seven  more  or 
less  complete  series.  Each  group  in  each  of  the  series 
2 and  3 are  represented  by  one  element.  “ The  octave 
appears  also  both  horizontally  and  vertically  in  the 
table.” 

169.  A New  System  of  the  Elements  by  Traube. — The 

fact  is  pointed  out  by  Traube(2i5)  that  certain  failings 
in  the  system  of  the  elements  as  given  by  Mendeleeff, 
based  upon  the  principle  that  the  properties  of  the  ele- 
ments are  periodic  functions  of  the  atomic  weights,  have 
been  generally  recognized.  In  various  instances  an  ele- 
ment does  not  receive  that  place  in  the  system  which 
should  belong  to  it,  because  of  its  chemical  relationship. 
In  many  cases  an  element  presents  resemblances  to  a 
number  of  elements  in  different  groups.  In  the  Mende- 
leeff system  only  one  place  can  be  assigned  to  it.  Finally 
the  very  probable  hypothesis  as  to  the  unity  of  matter 
speaks  against  the  probability  that  the  atomic  weights 
alone  should  decide  the  properties  of  the  elements. 

Thus  the  author  thinks  that  the  older  system  has  too 
one-sided  a principle  for  its  basis.  He  believes,  upon 
the  ground  of  his  researches  upon  the  atomic  and  molec- 


268 


THE  PERIODIC  LAW. 


ular  volumes  of  solution,  that  the  space  occupied  by  an- 
atom is  as  fundamental  a constant  as  its  mass  (atomic 
weight).  For  the  atomic  volumes  at  least  as  simple  re- 
lations obtain  as  for  the  atomic  weights.  Therefore  the 
law  might  be  written  : The  properties  of  the  elements  are 
functions  of  the  atomic  weights  and  of  the  atomic  vol- 
umes. The  elements  can  be  brought  into  a still  more 
natural  system  by  a consideration  of  the  atomic  volumes 
as  well  as  the  atomic  weights.  The  author  fails  to  ar- 
range such  a system,  however,  offering  only  series  of 
natural  families  for  consideration.  In  these,  the  same 
element,  according  to  valence,  finds  its  place  in  different 
series. 

The  first  natural  family  given  is  H,  Li,  Na,  Cu 
(monad),  Au  (monad),  and  Hg  (monad).  The  unit- 
ing bond  here  is  the  equivalence  of  the  atomic  volumes, 
as  the  atomic  weight  relations  are  by  no  means  simple. 
A branch  of  the  family  includes  ammonium  and  the  ele- 
ments sodium,  potassium,  rubidium,  caesium.  The  atomic 
volumes  of  the  four  elements  differ  by  about  io  units. 
The  volume  of  ammonium  is  equal  to  the  atomic  volume 
of  rubidium.  Thallium  (monad)  stands  near  to  potas- 
sium. Other  groups  are  discussed  in  a similar  manner. 
The  following  advantages  are  claimed  for  the  system. 

1 . The  inequalities  of  the  periodic  system  are  removed. 

2.  Even  where  no  simple  atomic  weight  relationship 
is  shown  between  nearly  related  elements,  the  bond  is 
furnished  by  the  simple  relations  of  the  atomic  volumes. 

3.  The  possibility  of  change  of  volume  on  the  part  of 
the  atoms,  the  “Polysterism,”  stands  in  close  causal  con- 


VENABLE’S  MODIFIED  ARRANGEMENT.  269 

nection  with  the  fact  that  an  atom  can  change  its  proper- 
ties and  its  valence  and  in  consequence  must  take  its 
place  in  different  families. 

With  full  recognition  of  the  services  rendered  by  the 
periodic  system  the  author  thinks  the  principle  proposed 
by  him  a step  forward  in  the  satisfactory  establishment 
of  the  properties  of  the  elements. 

170.  A flodified  Arrangement  of  the  Elements  by  Ven= 
able. — This  paper  (222)  contains  first  a criticism  of  cer- 
tain points  in  the  ta  bleof  Mendeleeff.  The  varying  length 
of  the  periods  ; the  anomalous  place  assigned  to  the 
triads,  or  tetrads,  Fe,  Co,  Ni,  and  Cu,  and  also  to  other 
single  elements  ; the  large  number  of  unknown  elements 
which  are  assigned  places  in  order  that  certain  known 
elements  may  fall  in  the  groups  to  which  their  other 
properties  would  naturally  assign  them,  and  similar 
difficulties  are  mentioned.  Thus  there  are  sixteen  ele- 
ments unknown  between  cerium  and  ytterbium  ; the 
third  great  period  of  seventeen  elements  contains  only 
four  known  ones  ; and  the  fifth  only  two  ; only  one  of 
the  five  great  periods  is  filled  out.  In  the  periodic  sys- 
tem arranged  by  Mendeleeff  there  are  sixty-four  known 
elements  and  thirty-five  empty  places. 

The  suggestion  is  then  made  that  in  order  to  obviate 
some  of  these  difficulties  the  idea  of  periodicity  be  sub- 
ordinated at  least  until  it  can  be  fully  proved.  This 
would  do  away  with  any  necessity  for  periods  of  seven 
or  seventeen.  The  really  essential  parts  of  the  natural 
system  are  that  the  elements  form  a continuous  ascend- 
ing series,  and  secondly  that  the  properties  are  deter- 


270 


THE  PERIODIC  LAW 


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THOMSEN’S  RATIONAL  ATOMIC  WEIGHTS.  27 1 

mined  by  the  atomic  weights  or  dependent  upon  them. 

The  new  table  is  built  up  as  follows  : At  the  head 
stand  seven  group  elements,  having  a difference  of  about 
2 between  their  atomic  weights.  These  can  also  be  called 
the  “ bridge  elements”  since  they  show  a notable  grada- 
tion of  properties  from  one  to  the  other  and  serve  as 
bridges  between  the  different  groups.  To  these  are 
linked,  with  a difference  in  atomic  weights  of  16,  seven 
“ typical  elements.”  These  elements  have  the  typical 
properties  and  characteristics  of  the  group  and  show  a 
wider  divergence  from  the  neighboring  groups.  From 
the  typical  element  of  each  group  diverge  two  sub-groups, 
generally  triads  though  they  may  be  changed  into 
tetrads  or  pentads  by  the  discovery  of  other  elements. 
These  show  fairly  regular  increments  in  the  atomic 
weights.  Much  stress  is  laid  upon  these  differences  be- 
tween the  atomic  weights  throughout  the  entire  arrange- 
ment. In  the  first  four  groups  the  left  or  positive  series  of 
three  is  most  like  the  type ; in  the  last  three  the  reverse  is 
true.  The  left  series  is  more  positive  and  the  right  more 
negative.  The  author  does  not  claim  originality  for  the 
arrangement  as  it  is  partly  given  in  the  work  of  Bayley, 
and  Wendt.  Nor  is  it  offered  as  of  special  theoretical 
value,  making  clear  any  law  of  nature  as  to  the  genesis 
of  the  elements,  but  rather  as  a help  in  systematizing 
the  teaching  of  chemistry. 

171.  The  Rational  Atomic  Weights  of  Thomsen. — 

Thomsen  (219)  took  as  the  basis  of  his  research , upon  what 
he  styles  a remarkable  relation  between  the  atomic 
weights,  his  recalculation  of  the  atomic  weights  as  given 


272 


THE  PERIODIC  LAW. 


by  Stas.  When  oxygen  is  taken  as  sixteen,  these  all 
vary  more  or  less  from  whole  numbers.  He  proposed  to 
multiply  these  by  some  common  factor,  which,  without 
changing  their  mutual  relations,  would  render  it  possi- 
ble to  assign  a common  cause  to  these  deviations  from 
integers.  From  a consideration  of  the  relation  found  by 
Stas  to  exist  between  the  atomic  weights  of  silver  and 
oxygen,  or  the  silver-oxygen  ratio,  Thomsen  deduced 
the  factor  1.00076.  If  the  atomic  weights  of  the  other 
simple  bodies  are  multiplied  by  this  factor  then  their 
differences  are  very  nearly  multiples  of  0.0120.  This 
would  seem  to  indicate  a common  cause  for  the  devia- 
tions. The  graphic  method  is  used  to  bring  out  the  rela- 
tion. Making  use  of  this  the  author  calculated  what  he 
called  the  rational  atomic  weights. 

172.  A Systematic  Groupingof  the  Elements  by  Thom= 
sen. — Julius  Thomsen  (234)  has  found  unsatisfactory  the 
grouping  of  the  elements  as  given  in  the  tables  of  Mende- 
leeff  and  Meyer.  One  of  the  chief  difficulties  lies  in  the 
large  number  of  rare  earth  metals  with  closely  approxi- 
mating atomic  weights. 

He  therefore  suggests  a new  grouping*  the  nature  of 
which  can  be  readiH  understood  from  the  table  appended 
to  his  article.  It  is  not  necessarj^  to  repeat  this  table 
here.  It  is  almost  identical  with  the  one  given  by  Ba}r- 
ley  and  afterward  used  by  Carnelley  (p.  175).  In  a 
private  communication  the  author  wrrites  that  the 
work  of  these  authors  was  entirely  unknowm  to  him.  In 
the  fifth  group  a difference  appears  between  the  two  ar- 
rangements. Bayley’s fifth  group  contains  nine  elements 


THOMSEN’S  GROUP  OF  INACTIVE  ELEMENTS.  273 

with  greater  atomic  weight  than  bismuth.  Thomsen 
limits  this  group  with  bismuth  as  third  and  last  member. 

Hydrogen  forms  the  head  of  Thomsen’s  table  ; the 
remaining  elements  are  divided  into  three  chief  groups 
of  which  the  first  contains  twice  seven  elements,  the 
second  twice  seventeen  and  the  third  thirty-one.  There 
is  perhaps  a fourth  of  thirty-one.  Thomsen  draws  atten- 
tion to  the  curious  fact  that  the  number  of  the  elements 
in  the  several  series  can  be  expressed  thus  : 

1+  2.3  -f-  2.5+  2.7  or  1,  7,  17,  and  31. 

The  two  first  groups  consist  of  two  series  each  but  the 
third  does  not  admit  of  division  into  series.  The  table 
is  intended  to  show  the  genetic  relationship  of  the  ele- 
ments. The  series  are  arranged  from  electro-positive  to 
electro-negative.  In  the  transition  from  the  first  to  the 
second  group  each  member  of  the  second  series  is  related 
to  two  members  of  the  third,  one  electro-positive  and  the 
other  electro-negative. 

173.  Thomsen’s  Group  of  Inactive  Elements. —Thom- 
sen (233)  draws  attention  to  the  transition  per  saltum  of 
Reynolds,  the  sudden  change  from  negative  to  positive, 
which  is  observed  in  passing  from  fluorine  to  sodium 
and  from  chlorine  to  potassium,  etc.  If  the  chemical 
character  of  the  elements  is  to  be  looked  upon  as  a 
periodic  function  of  the  atomic  weight  then  such  a func- 
tion must  follow  the  common  laws.  One  of  these  is  that 
in  the  passage  from  negative  to  positive  values,  and 
vice  versa , the  transition  must  be  either  through  zero, 
and  gradual,  or  through  infinity,  and  sudden.  The 
first  case  corresponds  to  the  gradual  change  in  electrical 


274 


THE  PERIODIC  DAW. 


character  in  a series  of  the  elements  in  the  periodic  sys- 
tem ; the  second  to  that  which  takes  place  in  passing 
from  one  series  to  another.  This  passage,  then,  mast 
take  place  through  an  element  whose  electrical  character 
is  ± o°,  that  is,  it  is  electrically  indifferent.  The  valence 
of  such  an  element  would  then  be  zero.  The  table  given 
shows  seven  series  of  elements  as  found  in  the  periodic 
system,  and  in  heavy  type  we  have  the  supposed  atomic 
weights  of  these  transition  elements  of  zero  valence. 


I.  Hydrogen  O i 4 

II.  Lithium — Fluorine  4 7 9 11  12  14  16  19  20 

III.  Sodium — Chlorine  20  23  24  27  28  31  32  35.5  36 

IV.  Potassium — Bromine  30  39  40  79  80  84 

V.  Rubidium — Iodine  84  85  87  125  127  132 

VI.  Caesium  132  133  137  212 

VII.  212 292 


The  author  goes  on  to  consider  the  formation  of  these 
elements  without  valence  from  an  hypothetical  primal 
matter.  The  nature  of  the  periodicity  is  then  to  be  ex- 
pressed by  means  of  trigonometric  and  elliptical  func- 
tions. 

If  the  atomic  weights  of  the  first  series  of  elements 
from  lithium  to  chlorine  be  inscribed  upon  a circle  whose 
periphery  is  32,  beginning  with  the  atomic  weight  four, 
of  the  first  inactive  element,  the  diagram  on  the  following 
page  is  gotten. 

It  is  immediately  seen  that  the  elements  of  the  first 
and  second  quadrant  are  electro-positive  and  those  of  the 
second  and  fourth  are  negative  and  those  have  the 
strongest  electrical  character  which  lie  nearest  to  the 


Thomsen’s  group  of  inactive  elements.  275 


horizontal  diameter.  Those  nearest  to  the  vertical 
diameter  do  not  show  so  definite  a character.  This 
behavior  brings  to  mind  the  function  cot  x , and  if  we 


character  of  all  the  elements  of  this  group  can  be  ex- 
pressed thus  : a-A. 

r e — cot — ~n. 

16 

Of  course  this  formula  does  not  express  the  absolute 
value  of  the  chemical  character  of  the  elements  but  only 
the  general  course  of  the  dependence  of  this  upon  the 
atomic  weights. 

Similarly  a mathematical  expression  for  the  dependence 
of  the  valence  upon  the  atomic  weights  is  worked  out 
and  found  to  be 


276 


THE  PERIODIC  LAW. 


Similar  relations  can  also  be  worked  out  for  the 
other  series.  The  author  thinks  that  this  hypothesis  of 
the  inactive  elements  combined  with  his  “ New  Group- 
ing of  the  Elements,”  already  mentioned,  brings  out  the 
periodicity  in  the  properties  of  the  elements  as  a contin- 
uous function  ; at  the  same  time  it  enables  one  to  see  the 
reason  for  the  arrangement  in  groups  of  two  series  ; and 
lastly,  it  considerably  lightens  the  task  of  the  future 
mathematical  treatment  of  the  whole  problem. 

The  mathematical  functions  of  Flavitsky  should  be 
compared  with  those  just  given. 

174.  The  System  of  Lecoq  de  Boisbaudran. — On 
several  occasions  this  distinguished  French  chemist  has 
intimated  that  he  was  busied  with  the  preparation  and 
perfection  of  a table  of  the  elements  which  should  pre- 
sent clearly  the  relationship  between  them.  Mhch  ex- 
pectation has  therefore  been  aroused  and  the  appearance 
of  the  table  has  been  looked  forward  to  with  much  inter- 
est. The  discussion  relative  to  the  properties  of  argon 
and  its  position  among  the  elements  probably  induced 
de  Boisbaudran  to  make  an  earlier  publication  than  he 
had  intended.  At  any  rate,  a paper  (263)  appeared  in 
March  1895,  giving  an  outline  of  the  chief  features  of  the 
table  but  manifestly  not  in  a perfected  form. 

All  will  agree  with  the  proposition  stated  by  the 
author,  at  the  outset,  that  the  classification  of  the  simple 
substances  presents  great  difficulties  and  that  errors  are 
easily  fallen  into.  Interesting  relations  are  sometimes 
met  with  on  classifying  the  elements  according  to  S3'S- 
teins  which  are  not  merely  different  but  incompatible. 


SYSTEM  OF  EECOO  DE  BOISBAUDRA.N.  277 

The  system  upon  which  he  had  been  engaged  for  some 
time  is  not  contradictory  to  that  of  Mendeleeff  but  is 
from  a different  point  of  view.  He  expressed  himself  as 
very  well  satisfied  with  its  predicting  powers. 

In  presenting  a sketch  of  his  system  to  the  public,  de 
Boisbaudran  promised  to  give  later  a more  detailed  ac- 
count. The  basis  of  the  system  is  the  selection  of 
certain  typical  characteristic  bodies  which  he  calls  the 
“ nodes.”  The  differences  between  the  atomic  weights, 
or  as  he  styles  them  the  “ variations,”  are  used  in  the 
building  up  of  the  table.  There  are  eight  families,  pos- 
sessing the  same  number  of  elements.  The  first  member 
of  each  family  is  derived  from  hydrogen.  The  nodes 
are  placed  in  one  plane  and  the  line  of  the  nodes  forms 
the  center  of  the  table. 

Setting  out  from  hydrogen,  each  family  is  formed  by 
five  successive  increments,  and  the  conditions  are  thus 
as  if  hydrogen  itself  resulted  from  another  increment 
brought  to  a smaller  element.  If  the  node  has  an  atomic 
weight  greater  than  that  of  hydrogen  by  at  least  32, 
then  two  elements  fall  between  them  ; if  less,  then  only 
one.  The  negative  elements  occupy  the  center,  the 
positive  the  extremities.  The  elements  of  even  and  odd 
atomicities  alternate  from  the  smallest  body  to  the  great- 
est. 

The  classification  is  compatible  with  the  hypothesis 
that  the  chemical  elements  are  in  reality  composed  of 
portions  of  matter  much  smaller  than  hydrogen.  This 
is  Prout’s  hypothesis,  by  extension.  Provisionally,  as 
a maximum  which  he  believes  too  high,  he  has  adopted 


278 


THE  PERIODIC  LAW. 


the  yVg'th  part  of  the  hydrogen  atomic  weight  for  the 
unit  employed  in  the  calculations.  The  table,  given  by 


de  Boisbaudran,  is 

as  follows  : 
(?w)" 

Bi' 

Pb” 

TP 

Ba" 

Cs' 

(?_$)" 

I' 

Te” 

Sb' 

Sn” 

In' 

Sr” 

Rb' 

(?£)" 

Br' 

Se” 

As' 

Ge" 

Ga' 

Ce” 

K' 

Cl' 

S” 

P' 

Si” 

Al'  Nodes 

Mg” 

Ge” 

Na 

Li 

(fy)" 

(?/?)” 

F' 

(?<*)' 

O” 

N' 

C" 

Bo' 

H 

H 

H 

H 

H 

H 

H 

H 

He  also  gave  a list  of  the  atomic  weights  of  the  first 
line  of  elements  calculated  from  hydrogen  “ using  simple 
empirical  relations”  which  he  failed  to  report.  It  is 
impossible,  therefore,  to  form  a just  idea  of  his  methods 
or  of  the  value  of  his  table.  As  to  the  formation  of  the 
elements,  he  thinks  that  this  must  depend  upon  the 
introduction  of  inequalities  between  the  masses  of  mat- 
ter, just  as  forces  result  from  inequalities  in  the  move- 
ments of  bodies.  In  each  case  there  is  compensation, 
+ 1 and — 1,  around  an  equilibrium  which,  when  once 
disturbed,  is  never  re-established.  “ The  fiction  by 
which  we  may  represent  the  formation  of  the  elements 
by  the  unequal  division  of  a primitive  mass  of  matter  is 
doubtless  imaginary.  Inequality  must  have  existed 
from  all  eternity  in  so-called  material  masses,  as  well  as 
in  motion,  by  reason  of  a necessity  alwaj^s  present,  the 
cause  of  which  escapes  us.  But  is  it  not  permissible  for 
us  to  suppose  that  the  material  inequalities  which  repre- 
sent the  elements  may  be  modified  as  may  the  vires  vivae , 
though  their  sum  always  remains  constant?”  Hitherto 
no  satisfactory  sign  of  a transformation  of  the  elements, 


GENESIS  OF  THE  ELEMENTS. 


279 


the  one  into  the  other,  has  been  observed  ; but  he 
remained  convinced  that  such  a transformation  is  realized 
daily  in  nature  under  the  influence  of  forces,  or  of  time, 
of  which  we  are  unable  or  ignorant  how  to  avail  our- 
selves. 

175.  Blanshard’s  Natural  Groups  and  Cross=Analogies. 

Blanshard  notes  (223)  that  the  existenceof  analogies  be- 
tween elements  in  different  groups  makes  classification 
difficult.  They  have  to  be  classed  from  the  point  of  view 
of  the  majority  of  their  properties.  The  author  points  out 
the  justice  of  Ostwald’s  criticism  of  Mendeleeff  ’s  Typical 
Elements.  These  are  really  links.  He  discusses  the 
analogies  of  various  elements  as  B and  C,  and  Cr,  Mn 
and  Cl,  A1  and  Be,  on  one  hand,  and  A1  and  Cr  and  Fe, 
on  the  other.  He  thinks  that  it  is  the  elements  occupy- 
ing corresponding  positions  in  the  natural  groups, 
especially  in  adjoining  groups,  that  show  these  cross- 
analogies and  speaks  of  a law  of  cross-analogies. 

176.  Solubility  as  a Clue  to  the  Genesis  of  the  Ele= 
ments. — In  a subsequent  paper  (261 ) Blanshard  attempts 
to  follow  out  the  clue  to  the  genesis  of  the  elements 
afforded  by  the  property  of  solubility.  He  is  apparently 
led  to  this  by  the  work  of  Belohoubek  upon  the 
solubilities  of  the  hydrocarbons.  Four  laws  are  deduced 
from  rather  meagre  tables  of  solubility  and  certain  rela- 
tions of  the  atomic  weights  are  pointed  out.  The  only 
bearing  upon  the  genesis  of  the  elements  must  lie  in  the 
similarity  to  the  compounds  of  carbon  and  hydrogen  and 
hence  it  may  be  reasoned  by  analogy  that  the  elements 
are  composite  in  nature. 


28o 


THE  PERIODIC  LAW. 


177.  The  netting  Points  of  the  Elements  as  a Clue  to 
Their  Genesis. — Blanshard  (225)  has  endeavored  to  find 
in  the  melting  points  some  clue  to  the  origin  and  inter- 
relation of  the  elements.  As  a starting  point  he  makes  use 
of  the  fact  observed  in  the  series  of  the  fatty  acids  and  in 
such  series  of  carbon  compounds  with  odd  and  even  num- 
bers of  carbon  atoms,  of  the  alternate  recurrence  of  high 
and  low  melting  points  with  each  increment  of  CH,.  He 
deduced  the  laws:  1.  With  elements  of  low  atomic  weight, 
the  melting  point  varies  directly  as  the  atomic  weight. 
2.  In  the  higher  periodic  series  of  elements  the  melt- 
ing points  are  alternately  high  and  low,  with  the  in- 
crease of  atomic  weight.  “ That  is  to  say,  in  all  but 
those  which,  from  their  low  atomic  weight,  may  reason- 
ably be  regarded  as  the  very  simplest,  a relationship 
maintains  which  has  been  observed  in  numerous  series 
of  organic  substances.  It  is  reasonable,  therefore,  to 
suppose  that  such  elements  with  higher  atomic  weights 
are  in  reality  substances  of  a higher  grade  than  others , 
in  that  they  resemble  such  highly  evolved  bodies  as 
carbon  compounds,  at  any  rate  in  respect  of  melting 
point.” 

Blanshard  has  also  considered  the  atomic  heats  (224, 
226),  the  specific  volumes  (227),  and  boiling  points 
( 244) , in  reference  to  the  Periodic  Law  and  the  genesis  of 
the.  elements.  The  arguments  are  deduced  from  analo- 
gies to  organic  compounds,  making  the  homologous 
series,  etc.,  of  this  branch  of  chemistry  a key  to  the 
value  of  the  elements. 


POSITION  OF  ARGON  AND  HELIUM. 


28l 


178.  The  Position  of  Argon  and  Helium  in  the  Peri= 
odic  System. — A considerable  proportion  of  the  papers 
published  upon  the  periodic  system  during  the  year  1895, 
have  borne  reference  to  the  position  to  be  assigned  the 
strange  new  elements  discovered  by  Rayleigh  and  Ram- 
say. Some,  as  Nasini  (221),  have  come  to  the  conclusion 
that  either  no  faith  is  to  be  put  in  the  deductions  from  the 
kinetic  theory  of  gases,  or  the  system  of  Mendeleeff  is  to 
be  cast  aside.  Others,  as  Mendeleeff  (236) , have  expressed 
their  confidence  in  the  system,  as  being  based  upon  too 
many  natural  facts,  and  confirmed  in  too  many  ways,  to 
be  overthrown  by  the  discovery  of  one  or  two  new  ele- 
ments with  apparently  irreconcilable  properties.  Others, 
as  Sedgwick  (231),  Reed  (232),  &c.,  have  claimed  to  have 
anticipated  the  discovery  of  argon,  at  least,  by  predictions 
from  their  systems.  Such  would  seem  to  be  the  position 
taken  by  de  Boisbaudran  andRang(2i3)also.  These  will 
find  itdifficulttokeeptheirpredictionsfully  in  accord  with 
the  changes  in  our  knowledge  of  che  properties  of  these 
new  elements.  A far  wiser  position  has  been  taken  by 
many  and  that  is  that  it  is  idle  to  attempt  to  fit  these  or 
any  other  supposed  elements  into  a rigid  system  when 
their  elemental  character  is  yet  in  question  and  their 
properties  most  imperfectly  known. 

From  the  preceding  pages  of  this  volume  it  can  be  seen 
that  the  system  is  incomplete  and  imperfect ; that  it 
allows  abundant  room  for  future  discoveries  and  that 
these  discoveries,  with  the  increased  knowledge  which 
they  imply,  can  not  fail  to  modify  the  system  in  some 
measure.  At  the  same  time  he  will  feel  sure  that  it  is 


282 


THE  PERIODIC  LAW. 


not  likely  to  be  overthrown  but  will  stand,  in  some  form, 
as  a great  natural  truth. 

179.  Victor  Meyer  on  the  Problems  of  the  Atoms. — 

Victor  Meyer  has  presented  in  this  lecture  (254)  the  argu- 
ments for  the  unity  of  matter.  The  insight  given  by  the 
periodic  system  into  the  connection  between  the  atomic 
weights  and  the  properties  of  the  elements  justifies  the 
assumption  that  the  forms  of  matter,  at  present  regarded 
as  elements,  are  really  of  a composite  nature. 

Perhaps  it  will  be  possible,  he  thinks,  by  means  of  a 
high  temperature  (3000°)  to  separate  many  apparent  ele- 
ments into  their  components.  Experiments  to  test  this 
have  been  undertaken  by  Meyer.  It  may  be  that,  by 
synthetic  means,  bodies  will  be  prepared  similar  to  the 
present  elements.  The  author  regarded  his  experiments 
with  iodonium  bases,  some  of  which  resemble  the  thal- 
lium compounds,  as  a ground  for  this  hope. 

180.  Lothar  Meyer’s  Account  of  the  Inception  of  the 
Periodic  System. — In  this  brief  treatise  (250)  Eotliar 
Meyer  has  given  the  world  his  last  words  upon  the  Pe- 
riodic Eaw.  One  of  the  papers  of  Dobereiuer  is  given, 
and  this  and  the  paper  of  Pettenkofer,  claiming  priority 
over  Dumas,  constitute  according  to  Meyer,  the  begin- 
ning of  the  Periodic  Law.  While  Pettenkofer  un- 
doubtedly gave  expression  to  some  of  the  ideas  con- 
tained in  Dumas’  Ipswich  address  rather  more  than  a 
year  before  this  address  was  delivered,  it  is  equally  cer- 
tain that  his  paper  did  not  follow  the  train  of  thought 
nor  contain  the  brilliant  speculations  which  attracted 
the  attention  of  the  world  to  the  address  of  Dumas.  For 


THE  COLOR  OF  THE  IONS. 


283 


eight  years  Pettenkofer’s  work  was  practically  unknown 
while  Dumas’  had  proved  an  incentive  to  a band  of 
earnest  workers  and  was  really  the  cause  of  Pettenkof- 
er’s republication.  It  may  be  patriotic  in  Meyer  to 
give  this  place  among  the  forerunners  of  the  Periodic 
Daw  to  Pettenkofer,  but  it  does  not  belong  to  him. 

Meyer  followed  up  these  papers  with  a brief  account  of 
the  further  development  of  the  system.  His  desire  to 
prove  the  justice  of  the  priority  claims  of  Pettenkofer 
has  led  him  to  make  some  unworthy  flings  against 
Dumas. 

181.  Lea  on  the  Color  of  the  Ions  and  the  Atomic 
Weight  Differences. — The  elements  are  divided  by  the 
author  (253)  into  three  classes;  those  whose  ions  are 
always  colorless,  those  whose  ions  are  always  colored, 
and  a smaller  (transitional)  class  whose  ions  are  colored 
at  some  valences  and  colorless  at  others. 

With  this  division  as  a basis,  the  elements  can  be  clas- 
sified, and  Dea  has  given  a table  of  them,  corresponding 
in  a measure  with  the  periodic  system.  The  elements 
of  the  third  class,  he  concludes,  have  nothing  in  common 
with  the  others,  cannot  be  classed  with  them  and  prob- 
ably have  a totally  different  constitution. 

Lea  devoted  some  space  in  his  paper  to  a discussion 
of  the  atomic  weight  differences,  giving  a systematic 
table  of  them,  yet  failing  to  bring  out  any  new  points. 

His  table,  based  upon  the  color  of  the  ions,  placed  the 
classes  mentioned  above  on  either  side  of  a straight  line, 
in  an  ascending  series,  connecting  the  two  sides  by 
means  of  the  transitional  elements. 


284 


THE  PERIODIC  LAW. 


182.  Flavitzky’s  Function  for  the  Deduction  of  the 
Properties. — In  1888  the  author  (166)  gave  an  expression 
of  the  Periodic  haw  as  a function  of  the  cotangent. 
This  has  already  been  referred  to  and  was  very  similar 
to  the  recent  work  of  Thomsen  (p.  275)  but  seems  to 
have  escaped  his  attention. 

In  a further  discussion  (256)  of  the  subject,  he  ex- 
presses the  dependence  of  the  properties  of  the  elements 
upon  their  atomic  weights  by  a formula  a cot  27c§(p). 
where  a is  a constant  depending  upon  the  choice  of  the 
measure  of  the  property  and  ${p)  any  function  of  the 
atomic  weight.  Since  there  is  no  definite  measure  of 
the  positive  or  negative  character,  a is  at  present  unde- 
termined. Still,  for  purposes  of  illustration,  the  for- 
mula is  made  use  of  by  Flavitzky  in  certain  calcula- 
tions. Thus  it  may  at  least  serve  for  the  deduction  of 
the  properties  qualitatively. 

183.  Tutton’s  Comparison  of  Isomorphous  Salts. — It 
is  not  possible  to  do  more  than  refer  to  this  excellent 
work  (259).  It  points  out  the  line  of  work  which  will 
in  the  future  enable  chemists  to  define  more  sharply  the 
periodic  system  and  to  bring  out  its  full  usefulness. 

The  plan  of  the  research  is  to  take  three  closely  allied 
elements  like  potassium,  rubidium,  and  caesium,  and  to 
determine  with  the  utmost  accuracy  the  physical  con- 
stants of  their  analogous  simple  and  double  salts.  This 
gives  a clue  to  the  effect  produced  by  replacing  an  ele- 
ment by  an  analogous  one  in  various  series  of  salts. 


An  Index  to  the 


LITERATURE  RELATING  TO  THE  PERIODIC  LAW. 


1.  Prout,  William.  (1815) 

On  the  Relation  between  the  Specific  Gravities  of  Bodies 
in  their  Gaseous  State  and  the  Weights  of  their  Atoms. 
Ann.  Phil.  (Thomson),  1815,  11,  321. 

2.  Prout,  William.  (1816) 

Correction  of  a Mistake  in  the  Essay  on  the  Relations  be- 
tween the  Specific  Gravities,  etc. 

Ann.  Phil.  (Thomson),  1816,  12,  hi. 

3.  Prout,  William.  (1833-1855) 

Chemistry  and  Meteorology.  Eighth  Bridgewater  Treat- 
ise. London,  1833.  4th  Ed.,  1855. 

4.  Meinecke,  Johann  Ludewig  Georg.  (1817) 

Ueber  die  Dichtigkeit  der  elastisch  fliissigen  Korper  im 
Verhaltniss  zu  ihrem  stochiometrischen  Werthen. 

J.  fiir  Chem.  (Schweigger ),  22,  138. 

5.  Doebereiner,  Johann  Wolfgang.  (1816) 

Report  from  Prof.  Wurzer  on  work  at  Jena. 

Ann.  der  Phys.  (Gilbert),  56,  332. 

6.  Doebereiner,  Johann  Wolfgang.  (1817) 

Ann.  der  Phys.  (Gilbert),  57,  436. 

7.  Doebereiner,  Johann  Wolfgang.  (1829) 

Versuch  zu  einer  Gruppirung  der  elementaren  Stoffe 
nach  ihrer  Analogie. 

Ann.  der  Phys.  (Pogg.),  15,  301. 

8.  Thomson,  Thomas.  (1825) 

An  Attempt  to  Establish  the  First  Principles  of  Chemistry. 
London,  1825. 

9.  Berzelius,  Johann  Jakob.  (1825-1831) 

a.  Lehrbuch  der  Chemie.  Dresden,  1825-31. 

b.  “ “ “ 1845,  3,  1178. 

10.  Gmelin,  Leopold.  ( 1827-1829) 

Handbuch  der  theoretischen  Chemie. 

Frankfurt-am-Main,  1827-29. 


286 


INDEX  TO  LITERATURE. 


11.  Turner,  Edward.  (1829) 

On  the  Composition  of  Chloride  of  Barium. 

Phil.  Trans.,  1829,  p.  291. 

12.  Turner,  Edward.  (1833) 

Experimental  Researches  on  Atomic  Weights. 

Phil.  Trans.,  1833,  p.  523. 

13.  Penny,  Frederick.  (1839) 

On  the  Application  of  the  Conversion  of  Chlorates  and 
Nitrates  into  Chlorides,  and  of  Chlorides,  into  Nitrates, 
to  the  Determination  of  Several  Equivalent  Numbers. 
Phil.  Trans.  1839,  p.  13. 

14.  Dumas  et  Stas.  (1841) 

Sur  le  veritable  Poids  Atomiques  du  Carbone. 

Ann.  Chim.  Phys.,  (3)  3,5. 

15.  Marignac,  Jean  Charles.  (1843) 

Quelques  Consequences  de  la  Loi  de  Prout. 

Schweizer  Gesell.  Verh.,  1843,  62-66. 

16.  Dumas,  Jean  Baptiste.  (1842) 

Recherches  sur  la  Composition  de  l’Eau. 

Comptes.  rend.,  14,  537- 

17.  Dumas,  Jean  Baptiste.  (1851) 

Address  before  the  British  Association  at  Ipswich,  1851. 
Brit.  Assoc.  Report  1851. 

The  Atheneum,  1851,  750. 

Am.  J.  Sci.,  (2),  12,  275. 

18.  Kremers,  P.  (1852) 

Ueber  die  Zusammenhang  des  specifischen  Gewichtes 
chemischer  Verbindungen  mit  ihrer  Auflosung  in  Was- 
ser  nebst  einer  daraus  abgeleiteten  Theorie  der  Wahl- 
verwandschaft.  (1852) 

Ann.  der.  Phys.  (Pogg.),  85,  56. 

19.  Kremers,  P.  (1853) 

Continuation  of  the  above. 

Ann.  der.  Phys.  (Pogg.),  85,  262. 

20.  Faraday,  Michael.  (1852) 

A Course  of  Six  Lectures  on  the  Non-metallic  Elements. 
Before  the  Royal  Institution,  London,  1S52. 


INDEX  TO  LITERATURE. 


287 


21.  Gladstone,  John  Hall.  (1853) 

Oil  the  Relation  between  the  Atomic  Weights  of  Analo- 
gous Elements. 

Phil.  Mag.,  (4),  5,  313. 

22.  Cooke,  Josiah  P.  (1854) 

The  Numerical  Relations  between  the  Atomic  Weights, 
with  Some  Thoughts  on  the  Classification  of  the  Chemi- 
cal Elements. 

Am.  J.  Sci.,  (2),  17,  387. 

23.  Kotikovsky.  (1854) 

Ueber  die  Nicht-einfachheit  der  Metalle,  des  Schwefels, 
der  Kohle,  des  Chlors,  u.  s.  w.  1854. 

Wein.,  8vo.  pp.  x,  118. 

24.  Low,  David.  (1854) 

On  the  Chemical  Equivalents  of  Certain  Bodies  and  on  the 
Relation  between  Oxygen  and  Azote. 

Phil.  Mag.,  24,  296. 

25.  An  Inquiry  into  the  Simple  Bodies  of  Chemistry.  (1856) 

Edinburgh,  1856,  8vo. 

26.  Lennsen.  (1857) 

Ueber  die  Gruppierung  der  Elemente  nach  ihren  chem- 
isch-physikalischen  Character. 

Ann.  Chem.  (Liebig),  103,  121. 

27.  Dumas,  Jean  Baptiste.  (1857-1858) 

Memoire  sur  les  equivalents  des  corps  simples. 

Comptes.  rend.,  45,  709;  46,  951  ; 47,  1026. 

28.  Odling,  William.  (1857) 

On  the  Natural  Groupings  of  the  Elements. 

Phil.  Mag.,  (3),  13,  423-439;  480. 

29.  Kremers,  P.  (1858) 

Ueber  die  Modification  der  Mittleren  Eigenschaft. 

Ann.  der  Phys.  (Pogg.),  99,  62. 

30.  Pettenkofer,  Max  von.  (1858) 

Ueber  die  regelmassigen  Abstande  der  Equivalentzahlen 
der  sogenannten  einfachen  Radicale. 

Miinchener  Gelehrten  Anzeigen,  30,  261-272. 

Ann.  Chem.  (Liebig),  105,  188. 

31.  Mercer,  John.  (1858) 

On  the  Relation  of  the  Atomic  Weights  of  the  Families  of 
the  Elements. 

Brit.  Assoc.  Report,  1858,  57. 


288 


INDEX  TO  LITERATURE. 


32.  Strecker,  Adolph.  (1859) 

Theorien  und  Experimente  zur  Bestimmung  der  Atomge- 
wichte  der  Elemente. 

Braunschweig,  8vo.  pp.viii,  146. 

33.  Schneider,  Franz  Coelestin.  (1859) 

Ueber  Aequivalente  der  Aequivalentbestimmungen  im  All- 
gemeinen. 

Ann.  der.  Phys.  (Pogg.),  107,  619. 

34.  Dumas,  Jean  Baptiste.  (1859) 

Memoire  sur  les  Equivalents  des  Corps  Simples. 

Ann.  chitn.  phys.,  (3),  55,  129-210. 

35.  Despretz,  Cesar  Mansuete.  (1859) 

Experiences  sur  quelques  Metaux  et  sur  quelques  Gaz. 
Comptes.  rend.,  48,  362. 

36.  Stas,  Jean  Servais.  (i860) 

Recherches  sur  les  Rapports  reciproques  des  Poids  atom- 
iques. 

Bull.  Acad.  Roy.  Belg.,  (2),  10,  208. 

37.  Marignac,  Jean  Charles.  (i860) 

Apropos  des  Recherches  de  Stas  sur  les  Rapports  recip- 
roques des  Poids  atomiques. 

Bibl.  Univ.  Archives  Sc.  Phys.  nat.,  9,  97-107. 

38.  Schafarik.  (1859) 

Ueber  einige  Vanadinverbindungen  und  die  Stellung  des 
Vanadins  im  Systeme. 

Ann.  Chem.  (Liebig),  iog,  100. 

39.  Lea,  M.  Carey.  (i860) 

On  Numerical  Relations  existing  between  the  Equivalent 
Numbers  of  Elementary  Bodies. 

Am.  J.  Sci.,  (2),  29,  98. 

40.  Ibid.,  (2),  29,  349. 

41.  Ibid.,  (2),  30,  399. 

42.  Cooke,  Josiah  P.  (i860) 

Crystalline  Form  not  necessarily  an  Indication  of  Definite 

Chemical  Composition. 

Am.  J.  Sci.,  (2),  30,  194. 

(1855) 

Apparent  Perturbation  of  the  Law  of  Definite  Proportions. 
Am.  J.  Sci.,  (2),  20. 


43- 


INDEX  TO  LITERATURE. 


289 


44.  Ouin,  C.  W.  (1861) 

Relation  between  the  Elementary  Equivalents. 

Chem.  News,  4,  253. 

45.  Lea,  M.  Carey.  (1862) 

The  Arithmetical  Relations  between  Chemical  Equiva- 
lents. 

Am.  J.  Sci.,  (2),  34i  387. 

46.  de  Chancourtois,  A.  E.  Beguyer.  (1862) 

Six  Memoirs  and  Notes  presented  to  the  Academie  des 
Sciences  from  April  7,  1862,  to  April  6,  1863.  Published 
as  one  Memoir  in  1863,  under  the  title, 

Vis  Tellurique.  Classement  naturel  des  Corps  Simples  ou 
Radicaux  obtenu  au  moyen  d’un  Systeme  de  Classifica- 
tion helicoidal  et  numerique. 

8vo,  pp.  21.  2 plates.  Paris.  1863. 

47.  Newlands,  John  A.  R.  (1863) 

On  Relations  among  the  Equivalents. 

Chem.  News,  7,  70. 

48.  Studiosus.  (1864) 

Chem.  News,  10,  11. 

49.  Ibid. 

Chem.  News,  10,  95. 

50.  Williamson,  Alexander  W.  (1864) 

On  the  Classification  of  the  Elements  in  Relation  to  their 
Atomicities. 

J.  Lond.  Chem.  Soc.,  (2),  2,211. 

51.  Noble,  J.  (1864) 

Numerical  Relations  of  Equivalent  Numbers. 

Chem.  News,  10,  120. 

52.  Inquirer.  (1864) 

Numerical  Relations  of  Equivalent  Numbers. 

Lond.  Chem.  News,  10,  156. 

53.  Newlands,  John  A.  R.  (1864) 

Relation  between  Equivalents. 

Chem.  News,  10,  59. 

54.  Ibid. 

Chem.  News,  10,  94. 

55.  Equivalent  of  Indium. 

Chem.  News,  10,  95  ; 240. 


290 


INDEX  TO  LITERATURE. 


56.  On  the  Law  of  Octaves.  (1865) 

Chem.  News,  12,  83. 

57.  On  the  Cause  of  Numerical  Relations  among  the  Equiva- 

lents. (1865) 

Chem.  News,  12,  4. 

58.  Fleck.  (1864) 

Relations  between  the  Chemical  Equivalents  and  the  Den- 

sities of  Bodies.  Monit.  Scient.,  (5),  29,  63. 

Abs.  in  Chem.  New,  9,  168. 

59.  Meyer,  Lothar.  (1864) 

Die  Modernen  Theorien  der  Chemie  und  ihre  Bedeutung 
fur  die  chemische  Mechanik. 

Breslau,  8vo. 

60.  Stas,  Jean  Servais.  (1865) 

Nouvelles  Recherches  sur  lesLois  desProprietes  chimiques. 
Memoires  Acad.  Roy.  Belg.,  35,  3. 

61.  Marignac,  Jean  Charles.  (1865) 

Remarques  sur  le  Memoire  de  M.  Stas,  intituld  : “Nou- 

velles Recherches  sur,  &c.” 

Ann.  Chem.  (Leibig),  Suppl.,  4,201-206. 

62.  Newlands,  John  A.  R.  (1866) 

On  the  Law  of  Octaves. 

Chem.  News,  13,  130. 

63.  Hinrichs,  Gustavos.  (1866) 

On  the  Spectra  and  Composition  of  the  Elements. 

Am.  J.  Sci.,  32.  350-363- 

64.  Programm  der  Atomechanik,  oder  die  Chemie  eine  Me- 

chanik der  Panatome.  (1867) 

Iowa  City,  4to,  p.  44. 

65.  Resumd  francais  der  Programme  de  l’Atomecanique. 

Iowa  City,  4to,  p.  4.  (1867) 

66.  Brodie,  Sir  Benjamin  C.  (1867) 

The  Ideal  Chemistry. 

J.  Lond.  Chem.  Soc.,  (2),  6,  367-466. 

67.  Hinrichs,  Gustavus.  (1869) 

On  the  Classification  of  the  Atomic  Weights  of  so-called 
Chemical  Elements  with  Reference  to  Stas’  Determina- 
tions. 

Amer.  Assoc.  Report,  18,  112-124. 


INDEX  TO  LITERATURE. 


291 


68.  Anonymous.  (1869) 

The  Numerical  Relations  of  the  Atoms — New  Elements 
Predicted. 

Chem.  News,  Amer.  Suppl.,  1869,  p.  217. 

69.  Anonymous.  (1869) 

The  Pairing  of  the  Elements. 

Chem.  News,  Amer.  Suppl.,  1869,  p.  339. 

70.  MendelEEFE,  Dmitri.  ^869) 

Essai  d’une  Systeme  des  Elements  d’apres  leurs  Poids 
Atomiques  et  Proprietes  Chimiques. 

J.  Russ.  Chem.  Soc.,  1869,  pp.  60-77. 

71.  Bemerkungen  liber  die  Anwendung  dieses  Systems  bei 

Vergleichung  der  Volumina  einfacher  Korper. 
Naturforscherversammlung  zu  Moskau,  S.  10  and  62. 

72.  Vortrag|iiber  die  Anwendung  dieses  Systems  bei  Vergleich- 

ung der  Formen  salzbildender  Oxyde.  (1869) 

J.  Russ.  Chem.  Soc,  1870,  14. 

73.  Abanderungen  an  den  Atomgewichten  einiger  Elemente 

und  iiber  die  Eigenschaften  einiger  zu  entdeckenden 
Elemente  auf  Grund  desselben  Systems.  (1870) 

J.  Russ.  Chem.  Soc.,  1871,  25. 

74.  Zur  Frage  iiber  das  System  der  Elemente.  (1871) 

Ber.  d.  chem.  Ges.,  4,  348-352. 

75.  Grundziige  der  Chemie.  (1868-1871) 

St.  Petersburg. 

76.  Die  periodische  Gesetzmassigkeit  der  Elemente. 

Ann.  Chem.  (Liebig.)  Suppl.,  8,  130-229. 

77.  Richter,  Victor  von.  (1869) 

Letter  from  St.  Petersburg. 

Ber.  d.  chem.  Ges.,  2,  553. 

78.  Blomstrand,  C.  W.  ( 1869) 

Die  Chemie  der  Jetztzeit. 

Heidelberg,  8vo,  20,  417. 

79.  Classification  der  Elemente.  (1870) 

Ber.  d.  chem.  Ges.,  3,  533. 

80.  Williamson,  Alexander  W.  (1869) 

Ber.  d.  chem.  Ges.,  2,  192. 

81.  Meyer,  Lothar.  (1870) 

Die  Natur  der  chemischen  Elemente  als  Function  ihrer 
Atomgewichte. 

Ann.  Chem.  (Liebig.)  Suppl.,  7,  354. 


292 


INDEX  TO  LITERATURE. 


82.  Baumhauer,  Heinrich.  (1870) 

Die  Bezeihungen  zwischen  dem  Atomgewichte  und  der 
Natur  der  cheraischen  Elemente. 

Braunschweig,  8vo,  p.  23. 

83.  Troizky.  (1870) 

Geometrische  Erklarung  d.  Bezeihungen  der  Elemente. 
Ber.  d.  chem.  Ges.,  3,  201. 

84.  Kopp,  Hermann.  (1874) 

Entwickelung  der  Chemie  in  der  neueren  Zeit. 

Miinchen,  1873,  8vo. 

85.  Kremers,  P.  (1869-1870) 

Physikalisch-chemische  Untersuchungen. 

Wiesbaden,  8vo. 

86.  Newiands,  John  A.  R.  (1872) 

Relations  between  the  Atomic  Weights  of  Cannizzaro. 
Chem.  News,  25,  252. 

87.  On  a Relation  between  the  Chemical  Grouping  of  Certain 

Elements  and  the  Quantities  in  which  they  exist  upon 


the  Earth’s  Surface.  (1872) 

Chem.  News,  26,  19. 

88.  Zaengerle,  Max.  (1871) 

Ueber  Atomgewichtsregelmassigkeiten. 

Ber.  d.  chem.  Ges.,  4,  570-574. 

89.  Griindriss  der  Chemie.  0872) 

Miinchen,  8vo. 

90.  Beomstrand,  C.  W.  (1873) 

Zur  Frage  iiber  die  Valenz  der  Elemente. 

Ber.  d.  chem.  Ges.,  4,  652. 

91.  Meyer,  Lothar.  (1873) 

Zur  Systematik  der  anorganischen  Chemie. 

Ber.  d.  chem.  Ges.,  6,  101-106. 

92.  Knowles,  F.  C.  (1874) 


On  the  True  Relation  between  the  Weights,  Volumes,  and 
Specific  Gravities  of  the  Component  Elements  and 
Those  of  the  Compounds  in  Chemical  Combination. 
Chem.  News,  30,  199. 


INDEX  TO  LITERATURE. 


293 


93.  Roscoe,  Sir  Henry  E.  (1:874) 

Some  Remarks  on  Dalton’s  First  Table  of  Atomic 
Weights. 

Chem.  News,  30,  266-267. 

94.  Groshans,  J.  A.  (1872-1873) 

Natur  der  Elemente. 

Ber.  d.  chem.  Ges.,  5,  625,  689,  754;  6,  519,  523,  704, 

1079,  1295,  1354. 

95.  Gibbes,  L.  R.  (1875) 

Synoptical  Tables  of  the  Elements. 

Elliott  Society,  Charleston,  pp.  77-90. 

96.  Wiik,  F.  J.  (187S) 

Forsok  till  eu  pa  Atomgewigten  Grundad  Gruppering 
af  de  kemiska  Elementerna.  Helsingfors,  1875. 

Acta.  Soc.  Sc.  Feun.  Tom.,  10,  416-437. 

97.  Simmen.  (1876) 

Constitution  der  chemischen  Elemente  und  deren  Ver- 
bindungen. 

Basel,  1876,  4to. 

98.  Odling,  Wiluam.  (1877) 

On  Gallium. 

Brit.  Assoc.  Rep.  1877. 

99.  Mendeleeff,  Dmitri.  (1873) 

Atomgewichte  von  Ce,  La,  Di. 

Ber.  d.  chem.  Ges.,  6,  558. 

100.  Bemerkungen  zu  den  Untersuchungen  v.  Groshans  iiber 

die  Natur  der  Elemente.  ( 1874) 

Ber.  d.  chem.  Ges.,  7,  128. 

101.  An  announcement  from  St.  Petersburg  of  the  correspon- 

dence of  Ga  with  Ekasilicon.  (1875) 

Ber.  d.  chem.  Ges.,  8,  1680. 

102.  La  Loi  periodique  des  Elements  chimiques.  (1876) 

Paris,  4to,  1879. 

103.  Marignac,  Jean  Charles.  ( 1877) 

Sur  les  Equivalents  chimiques  et  les  Poids  Atomiques 
corume  Base  d’un  Systeme  de  Notation. 

Moniteur  Scient.,  7,  920. 

104.  Newlands,  John  A.  R.  (1878) 

On  Relations  among  the  Atomic  Weights  of  the  Elements. 
Chem.  News,  37,  255. 


294 


INDEX  TO  LITERATURE. 


105.  Dumas,  Jean  Baptiste 

Sur  la  Presence  de  l’Oxygene  dans  l’Argent  metallique. 
Comptes.  rend.,  86,  65. 

106.  Waechter,  Fr.  (1878) 

Bezeihungen  zwischen  den  Atomsgewichten  der  Ele- 
mente. 

Ber.  d.  chem.  Ges.,  11,  11-16. 

107.  Lockyer,  J.  Norman.  (1878) 

Discussion  of  the  Working  Hypothesis  that  the  so-called 
Elements  are  Compound  Radicals. 

Read  before  Royal  Soc.,  Dec.  12,  1878,  Nat.  19,  197. 

108.  Berthelot,  Marcellin.  (1879) 

On  the  Nature  of  the  Chemical  Elements. 

Chem.  News,  39,  171. 

109.  Crookes,  W.  (1879) 

The  Dissociation  of  the  Elements. 

Chem.  News,  39,  65. 

no.  Carnelley,  Thomas.  (1879) 

Relations  between  the  Atomic  Weight  and  Certain  Physi- 
cal Properties. 

Chem.  News,  39,  281-282. 
hi.  Influence  of  Atomic  Weights. 

Phil.  Mag.  (5),  7,  305,  368,  461. 

112.  Lersch,  B.  M.  (1879) 

Die  Zahlenverhaltnissen  des  Planetensystems  und  die 
Atomgewichte. 

Liepzig,  8vo.  1879,  p.  64. 

113.  Potilizin.  (1877) 

Gesetz  der  Verdrangung  von  Cl  durch  Br  im  Natiirlichen 
System. 

Ber.  d.  chem.  Ges.,  9,  1025-1027. 

114.  Mallet,  J.  W.  (1SS0) 

Revision  of  the  Atomic  Weight  of  Aluminum. 

Am.  Chem.  J.,  3,  95. 

115.  Gibertini,  Dario.  (1880) 

Reciprocal  Relations  between  the  Atomic  Weights  of  the 
Elements  and  their  Properties.  Abs.  Jahresber.  18S0. 
L’Orosi  giornale  di  chim.  farm,  e sc.  aff.  1S80,  No.  1. 


INDEX  TO  LITERATURE. 


295 


116.  Meyer,  Lothar.  (1880) 

Zur  Geschichte  der  periodischen  Atomistik. 

Ber.  d.  chem.  Ges.,  13,  259-265  ; 2043. 

1 17.  MendelEEff,  Dmitri.  (1880) 

Zur  Geschichte  des  periodischen  Gesetzes. 

Ber.  d.  chem.  Ges.,  13,  1796-1804. 


118.  Ciamician.  (1881) 

Ueber  die  Spektren  der  chemischen  Elemente  und  ihrer 
Verbindungen. 

Wien.  Sitzungsber,  72,  138-144;  76,  499-517. 

119.  Spring,  W.  (1881) 

Tableau  representant  la  Loi  Periodique  des  Elements 
Chimiques. 

Liege,  1881. 


120.  BoutlEROW,  A.  M.  (1882) 

Remarks  on  the  Atomic  Weights. 

J.  Russ.  Chem.  Soc.,  1882,  208-212. 

121.  Zaengerle,  Max.  (1882) 

Ueber  die  Natur  der  Elemente. 

Program  des  konigl.  Realgym.  Miinchen,  1882. 

122.  Chase,  Pliny  Earle.  (1882) 

Polydynamic  Notes. 

Amer.  Phil.  Soc.  1882. 


123.  Clarke,  F.  W.  (1882) 

A Recalculation  of  the  Atomic  Weights. 

Smithsonian  Institution,  1882,  280. 

124.  Bayley,  Thomas.  (1882) 

On  the  Connection  between  the  Atomic  Weights  and  the 
Chemical  and  Physical  Properties  of  the  Elements. 

Phil.  Mag.,  (5),  13,  26. 

125.  Boutlerow,  M.  A.  (1882) 

Notice  sur  les  Poids  Atomiques. 

Bull.  Soc.  Chim.  (nouv.  ser.),  39,  263. 

126.  Schdtzenberger,  M. 

Remarks  on  preceding  paper. 

Bull  Soc.  Chim.  (nouv.  ser.),  39,  258.  ‘ 

127.  Fedaroff.  (1882) 

Relation  between  the  Atomic  Weights  and  the  Elementary 
Bodies. 

Abs.  J.  Chem.  Soc.  1882,  p.  359. 

Bull.  Soc.  Chim.,  (2),  36,  559-560. 


296  INDEX  TO  LITERATURE. 

128.  Hartley,  W.  N.  (1882) 

Note  on  certain  Photographs  of  the  ultra-violet  Spectra  of 
the  Elementary  Bodies. 

J.  Lond.  Chem.  Soc.,  1881,  84. 

129.  On  Homologous  Spectra.  (1883) 

J.  Chem.  Soc.,  1883,  pp.  390-400. 

130.  Meyer,  Lothar,  and  Seubert,  Karl.  (1883) 

Die  Atomgewichte  der  Elemente  aus  den  Originalzahlen 
neu  berechnet. 

Leipzig,  1883,  8vo.  11,  245. 

131.  Gladstone,  J.  H.  (1883) 

Address  before  the  Chemical  Section  of  the  British  Asso- 
ciation. 

Chem.  News,  48,  151. 

132.  Laurie,  A.  P.  (1883) 

Relations  between  the  Heats  of  Combinations  of  the  Ele- 
ments and  their  Atomic  Weights. 

Phil.  Mag.,  (5),  15.  42. 

133.  Gerber,  Maximilian.  (1S83) 

Ueber  die  Prout’sche  Hypothese. 

Bull.  Soc.  Chim.,  (2),  39,  562.  - 

134.  Pelopidas.  (1883) 

Ueber  die  Anwendbarkeit  der  Grundziige  des  periodischen 
Gesetzes  der  Elemente  auf  organische  Verbindungen. 

J.  Russ.  Chem.  Soc.,  1883,  364. 

135.  Gretschel  und  Bornemann.  (1S83) 

Das  Natiirliche  System  der  Elemente. 

Jahrbuch  der  Erfiuduugen,  I9ten  Jahrgang,  241-306. 
Leipzig. 

136.  Cooke,  Josiah  P.  (1883) 

Possible  Variability  of  the  Law  of  Definite  Proportions. 
Am.  J.  Sci.,  (3),  26,  310. 

137.  Mills,  E.  J.  (ISS4) 

On  Melting  Points  and  Boiling  Points  as  Related  to 
Chemical  Composition. 

Phil.  Mag.,  (5),  17,  173- 

138.  Carnelley,  Thomas.  (1884) 

The  Periodic  Law  extended  to  certain  Physical  Proper- 
ties. 

Phil.  Mag.,  (5),  18,  1-22. 


INDEX  TO  LITERATURE. 


297 


139.  Carnelley,  Thomas. 

On  the  Color  of  Chemical  Compounds  as  a Function  of  the 
Atomic  Weights  of  their  Constituent  Elements. 

Ibid.,  p.  130. 

140.  On  the  Periodic  Law  and  the  Occurrence  of  the  Elements 

in  Nature. 

Ibid.,  p.  194. 

141.  Groshans,  J.  A.  (1884) 

Ueber  die  Isomorphen  Korper  in  Bezeihung  zum  neuen 
Gesetz. 

Rec.  Trav.  Chim.,  4,  105-124. 

142.  Meyer,  Victor. 

The  Transformation  in  the  Theory  of  Atoms. 

Cosmos  les  Mondes,  1884,  No.  VIII. 

143.  Huth,  Ernst.  (1884) 

Das  periodische  Gesetz  der  Atomgewichte  und  das  natiir- 
liche  System  der  Elemente. 
pp.  16,  with  figure  Frankfurt  a.  O.  1884. 

144.  Groshans,  J.  A.  (1884) 

Ueber  die  Beriihrungspunkte  zwischen  dem  periodischen 
Gesetz  von  Mendeleeff  und  dem  Gesetze  der  Densitats- 
zahlen. 

Rec.  Trav.  Chim.,  3,  310. 

145.  Berthelot,  Marcellin.  (1885) 

Les  Origines  de  l’Alchimie. 

Paris,  1885,  8vo,  pp.  308-314. 

146.  Meyer  und  Seubert.  (1885) 

Ueber  die  Einheit  der  Atomgewichte. 

Ber.  d.  chem.  Ges.,  18,  1089-1097. 

147.  Das  Atomgewicht  des  Silbers  und  Prout’s  Hypothesis. 
Ibid.,  18,  1097-1104. 

148.  Meyer,  Lothar.  (1885) 

Ueber  die  neuere  Entwickelungder  chemischenAtomlehre. 
Math,  naturw.  Mitteilungen.  3,  1885,  24. 

149.  Ostwald,  Wilhelm.  (1885) 

Lehrbuch  der  allgemeinen  Chemie. 
pp.  126-127. 

150.  Carnelley,  Thomas.  (1885) 

Suggestions  as  to  the  Cause  of  the  Periodic  Law  and  the 
Nature  of  the  Chemical  Elements.  Brit.  Assoc.  1885. 
hem.  News,  53,  157-159,  169-172,  183-186,  197. 


298  INDEX  TO  LITERATURE. 


151.  Rydberg,  J.  R.  (1885) 

Om  de  Kemiska  Grundamnenas  Periodiska  System, 
p.  31,  2 fig.  Bihang  till  k.  Svenska  Vet.  Akad. 

Handl.  Bd.  No.  2. 

152.  Die  Gesetze  der  Atomgewichtszahlen.  (1886) 

Bihang  till  k.  Sv.  Vet.  Akad.  Handl.  Bd.  No.  13. 

153.  Hartley,  W.  N.  (1885) 

The  Influence  of  Atomic  Arrangement  on  the  Physical 
Properties  of  Compounds. 

Phil.  Mag.,  [5],  19,  55. 

154.  Carnelley,  Thomas.  (1885) 

The  Periodic  Law  as  Illustrated  by  Certain  Physical  Prop- 
erties of  Organic  Compounds. 

Phil.  Mag.,  [5],  20,  259-497. 

155.  Reynolds,  J.  Emerson.  (1886) 

Note  on  a Method  of  Illustrating  the  Periodic  Law. 

Chem.  News,  54,  1-4. 

156.  Crookes,  William.  (1886) 

Address  to  the  Chemical  Section  of  the  British  Association. 
Chem.  News,  54,117-126. 

157.  Dulk,  L.  (1885) 

Ueber  Gravitation  und  Atomgewicht. 

Ber.  d.  chem.  Ges.,  18,  432-438. 

158.  Ibid.,  19,  932-942.  (1886) 

159.  Phipson,  T.  L.  (1886) 

Outlines  of  a New  Atomic  Theory. 

London,  4to.  pp.  4. 

160.  Mills,  E.  J.  (1885) 

On  the  Numerics  of  the  Elements.  Pt.  1. 

Phil.  Mag.,  [5],  18,  393. 

161.  On  the  Numerics  of  the  Elements.  Pt.  11.  (1886) 

Phil.  Mag.,  [5],  21. 

162.  Newlands,  John  A.  R.  (1884) 


On  the  Discovery  of  the  Periodic  Law  and  on  Relations 
among  the  Atomic  Weights. 

i2mo.  pp.  39.  A republication  of  previous  papers  in  the 
Chemical  News. 


INDEX  TO  LITERATURE. 


299 


363.  Crookes,  William.  (1887) 

The  Genesis  of  the  Elements.  Royal  Inst.  Feb.  18,  1886. 
Chem.  News,  55,  83-88  ; 95-99. 

164.  Reed,  C.  J.  (1885) 

The  Graphical  Representation  of  the  Relation  between 
Valence  and  Atomic  Weight. 

Trans.  St.  Louis  Acad.  Sci.,  4,  No.  4. 


165.  Gruenwald,  Anton.  (18871 

Remarkable  Relations  between  the  Spectrum  of  Watery 
Vapor  and  the  Line  Spectra  of  Hydrogen  and  Oxygen, 
and  of  tha  Chemical  Structure  of  the  Two  Latter  Bodies 
and  Their  Dissociation  in  the  Atmosphere  of  the  Sun. 

Chem.  News,  56,  186,  201,  223,  232. 

166.  Flavitzky,  Flavian.  (1887) 

A Function  Expressing  the  Periodicity  of  the  Chemical 
Elements. 

Kazan.  8vo.  pp.  16.  1 plate. 


167.  Bazaroff.  (1887) 

The  Atomic  Weights  of  the  Elements. 

J.  Russ.  Chem.  Soc.,  1887,  67-73. 

168.  Thomsen,  Julius.  (1887) 

Om  Materiens  Enhed.  pp.  38.  Copenhagen. 

169.  Roberts — Austen,  W.  C.  (1888) 

Mechanical  Properties  of  Metals  in  Relation  to  the  Pe- 
riodic Law. 

Proc.  Roy.  Soc.,  43,  425-428. 

170.  Vogel,  E.  (1888) 

The  Atomic  Weights  and  their  Variation. 

San  Francisco,  1888,  pp.  114. 

171.  Livermore,  W.  R.  (1888) 

Classification  of  the  Atomic  Weights  in  Two  Ascending 


Series  Corresponding  to  the  Groups  of  Artiads  and  Per- 
issads. 

Proc.  Amer.  Acad.  Arts  and  Sci.,  24,  164-175. 

172.  Pearson,  K.  (1888) 

A Certain  Atomic  Hypothesis. 

Cambridge  Phil.  Trans.,  14,  71-100. 

173.  Stoney,  G.  Johnstone.  (1888) 

On  the  Logarithmic  Law  of  the  Atomic  Weights. 

Royal  Soc.,  April  19,  1888.  Chem.  News,  57,  163. 


300 


INDEX  TO  LITERATURE. 


174.  DELAUNEY.  (1888) 

Equivalents  of  the  Elements. 

Comptes  Rend.,  106,  1405-1407. 

175.  Haughton,  S.  (1888) 

Geometrical  Illustrations  of  Newlands  and  Mendeleeff’s 
Periodic  Law  of  the  Chemical  Elements. 

Royal  Irish  Acad.,  1888.  Chem.  News,  58,  93-95  ; 102-103. 

176.  Gruenwald,  Anton.  (1888) 

Definition  of  Chemical  Atoms. 

Proc.  Imp.  Acad.  Sci.,  Vienna,  95,  Chem.  News,  58,  309. 

177.  Hartley,  W.  N.  (1888) 

A Definition  of  the  Term  Atomic  Weight  and  its  Refer- 
ence to  the  Periodic  Law. 

Proc.  Chem.  Soc.,  1888,  66-67. 

178.  Brauner,  Bohuslav.  (1888) 

The  Standard  of  the  Atomic  Weights. 

Chem.  News.,  58,  307. 

179.  Venable,  F.  P.  (1888) 

Recalculations  of  the  Atomic  Weights. 

Elish.  Mitch.  Soc.,  1888.  J.  Anal.  Chem.,  3,  48-61. 

180.  Stransky,  Sigmund.  (1889) 

Numerical  Relations  of  the  Atomic  Weights. 

Monat.  Chem.,  10,  19-25. 

181.  Mendeleeff,  Dmitri.  (1889) 

The  Periodic  Law  of  the  Chemical  Elements. 

Faraday  Lecture. 

J.  Chem.  Soc.,  1889,  pp.  634-656. 

182.  Cooke,  Josiah  P.  (1889) 

The  Chemical  Elements. 

Popular  Science  Monthly,  34,  733-750. 

183.  Remsen.Ira.  (1S89) 

The  Chemistry  of  To-day. 

Popular  Science  Monthly,  34,  591-597. 

184.  Gruenwald,  Anton.  (1889) 

Spectrum  Analysis  of  Cadmium. 

Chem.  News,  59,  2,  16,  29. 

185.  Ames,  Joseph,  S.  (1887) 

Griinwald’s  Mathematical  Spectrum  Anal}-sis. 

Am.  Chem.  J.,  11,  138-141. 


INDEX  TO  LITERATURE. 


301 


186.  Delauney.  (1889) 

Atomic  Weights  of  the  Elements. 

Comptes  Rend.,  109,  526-527. 

187.  Buehler,  Wilhelm.  (1889) 

Zwei  Materien  mit  drei  Fundamental-Gesetzen  uebst  einer 
Theorie  der  Atome. 
pp.  62.  Stuttgart. 

188.  Groshans,  J.  A.  (1889) 

Prout’s  Hypothesis — especially  with  Reference  to  the 
Atomic  Weights  of  Carbon  and  Oxygen. 

Rec.  Trav.  Chim.,  7,  358-364. 

189.  Meyer  und  Seubert.  ( 1889) 

Die  Einheit  der  Atomgewichte. 

Ber.  d.  chem.  Ges.,'22,  872  ; 1161  ; 1392. 

190.  Brauner,  Bohuslav.  (1889) 

Die  Basis  der  Atomgewichte. 

Ber.  d.  chem.  Ges.,  22,  1186-1192. 

191.  Ostwald,  Wilhelm.  (1889) 

Ueber  die  Einheit  der  Atomgewichte. 

Ber.  d.  chem.  Ges.,  22,  1021-1024  ; 1721-1722. 

192.  Kronberg.  (1890) 

Das  Cubiponderalgesetz,  die  Hypothese  vom  Atom-Iso- 
morphismus  und  die  Specifische  Natur  der  Elemente. 
Naturw.  Wochenschrift,  5,  301-302. 

193.  Tchitcherine,  B.  (1890) 

Le  Systeme  des  Elements  chimiques. 

Bull.  Soc.  Imp.  des  Nat.  de  Moscou,  1890,  1. 

194.  Sutherland,  W.  (1890) 

New  Periodic  Property  of  the  Elements. 

Phil.  Mag.,  (5),  30,  318-323. 

195.  Carnelley,  Thomas. 

Approximate  Algebraic  Expression  of  the  Periodic  Raw. 
Phil.  Mag.,  (5),  29,  97-115. 

196.  RoberTS-Austen,  W.  C.  (1891) 

Certain  Properties  of  Metals  considered  in  Relation  to  the 
Periodic  Law. 

Proc.  Roy.  Soc.,  49.  347-356- 

197.  Noyes,  W.  A. 

The  Unit  for  Atomic  Weights. 

J.  Anal.  Appl.  Chem.,  5,  36-39. 


(1891) 


302 


INDEX  TO  LITERATURE. 


198.  DeBoisbaudran  et  Lapparent.  (1891) 

Sur  une  Reclamation  de  Priority  en  Faveur  de  M.  de  Chan- 
courtois  relativement  aux  Relations  numeriques  des 
Poids  Atomiques. 

Comptes  Rend.,  113,  77. 


199.  Crookes,  William. 

(1891) 

The  Telluric  Screw. 

Chem.  News,  63,  51. 

200.  Kayser  and  Runge. 

(1891) 

On  the  Line  Spectra  of  the  Elements  of  Mendeldeff’s  Sec- 
ond Group. 

Phil.  Mag.,  (5),  31,  368. 

201.  Wendt,  Gustav.  (1891) 

Die  Entwickelung  der  Elemente — Entwurf  zu  einer  bio- 
genetischen  Grundlage  fiir  Chemie  und  Physik. 

Berlin,  1891.  pp.  49.  1 plate. 

202.  Bassett,  Henry.  (1892) 

A Tabular  Expression  of  the  Periodic  Relations  of  the  El- 
ements. 

Chem.  News,  65,  3 4;  19. 

203.  Wilde,  Henry.  (1892) 

On  the  Origin  of  Elementary  Substances,  and  on  Some 
New  Relations  of  their  Atomic  Weights, 
pp.  vi,  17,  I plate,  London. 

204.  Preyer,  W.  (1891-1893) 

Ueber  das  genetische  System  der  chemischen  Elemente. 
Berlin  Phys.  Ges.,  10,  85-88. 

205.  Einige  thatsachliche  Grundlagen  desgenetischen  Systems 

der  Elemente. 

Berlin  Pharm.  Ges.,  1892,  144-155. 

206.  Das  genetische  System  der  chemischen  Elemente.  p.  104. 
Berlin,  1893. 

207.  Adkins,  Henry.  (1892) 

Relations  between  the  Atomic  Weights. 

Chem.  News,  65,  123. 

208.  Meusel,  Eduard. 

Der  Monismus  der  chemischen  Elemente. 

Liegnitz,  pp.  58.  6 plates. 


(i393) 


INDEX  TO  LITERATURE. 


303 


209.  Wislicenus,  Johannes.  (1893) 

Die  Chemie  und  das  Problem  von  der  Materie. 

Rede  an  der  Universitat  zu  Leipzig. 

210.  Meyer,  Lothar.  (1893) 

Ueber  den  Vortrag  der  anorganischen  Chemie  nach  dem 
natiirlichen  Systeme  der  Elemente. 

Ber.  d.  chem.  Ges.,  26,  1230-1250. 

211.  Palmer.  (1890-1893) 

The  Nature  of  the  Chemical  Elements. 

Proc.  Col.  Scient.  Soc.,  3.  287-307;  4>  33-74  1 165-173;  355- 

364- 

212.  deeley,  r.  m.  (1893) 

A New  Diagram  and  Periodic  Table  of  the  Elements. 

J.  Chem.  Soc.,  1893,  852-867. 

213.  Rang,  F.  (1893) 

The  Periodic  Arrangement  of  the  Elements. 

Chem.  News,  67,  178. 

214.  Bailey,  G.  H.  (1894) 

The  Stability  of  the  Oxides  considered  in  Relation  to  the 
Periodic  Law. 

J.  Chem.  Soc.,  1894,  315-320. 

215.  Traube,  J.  (1894) 

Die  Grundlagen  eines  neuen  Systems  der  Elemente. 

Ber.  d.  chem.  Ges.,  27,  3179-3181. 

216.  Deeley,  R.  M.  (1894) 

The  Oxides  of  the  Elements  and  the  Periodic  Law. 

J.  Chem.  Soc.,  1894,  106-115. 

217.  Hinrichs,  Gustavus.  (1894) 

The  True  Atomic  Weights  of  the  Chemical  Elements  and 
the  Unity  of  Matter. 

St.  Louis,  pp.  xiv,  255. 

218.  Pattison-Muir,  M.  M.  (1894) 

The  Alchemical  Essence  and  the  Chemical  Element. 
London.  8vo.  pp.  94. 

219.  Thomsen,  Julius.  (1894) 

Relation  Remarquable  entre  les  Poids  Atomiques  des  Ele- 
ments chimiques.  Poids  Atomiques  Rationnels. 

Bull,  de  l’Acad.  Roy.  de  Danemark.  1894,  pp.  325-343. 


3°4 


INDEX  TO  LITERATURE. 


220.  TuTTON,  A.  E.  (1894) 

Connection  between  the  Atomic  Weights  of  combined 
Metals  and  the  Crystallographical  Character  of  Isomor- 
plious  Salts. 

J.  Chem.  Soc.,  165,  628-717. 

221.  Nasini,  R.  (1895; 

Observations  concerning  Argon. 

Gaz.  Chim.  Ital.,  25,  37-46. 

222.  Venable,  F.  P.  (1895) 

A Modified  Arrangement  of  the  Elements  under  the  Nat- 
ural Law. 

J.  Am.  Chem.  Soc..  17,  75-84. 

223.  Blanshard,  C.  T.  (1895) 

Natural  Law  and  Cross-Analogies. 

Chem.  News,  71,  39-40. 

224.  The  Role  of  the  Atomic  Heats  in  the  Periodic  System  of  the 

Elements. 

Phil.  Mag.,  (5),  39.  106-115. 

225.  The  Melting  Points  of  the  Elements  as  a Clue  to  their  Gen- 

esis. 

Chem.  News,  71,  285. 

226.  The  Atomic  Heat  in  relation  to  the  Periodic  System  of  the 

Elements. 

Phil.  Mag.,  (5),  39.  106-115. 

227.  Specific  Volume  and  the  Genesis  of  the  Elements. 

Chem.  News,  72,  230. 

228.  Wilde,  Henry.  (1895) 

On  the  Multiple  Proportions  of  the  Atomic  Weights  of  the 
Elementary  Substances  in  relation  to  the  Unit  of  Hy- 
drogen. 

Manchester  Lit.  and  Phil.  Soc.,  1895,  67-85. 

229.  Rayleigh  and  Ramsay.  (1895) 

Argon — a new  Constituent  of  the  Atmosphere. 

Roy.  Soc.,  Jan.  31,  1895.  Chem.  News,  71,  57-58. 

230.  Stoney,  G.  Johnstone.  (1895) 

Argon — a Suggestion. 

Chem.  News,  71,  67-68. 

231.  Sedgwick.  (1895) 

The  Existence  of  an  Element  without  Valency,  of  the 
Atomic  Weight  of  Argon,  anticipated  before  the  discov- 
ery of  Argon,  etc. 

Chem.  News,  71,  139-140. 


INDEX  TO  LITERATURE. 


3°5 


232.  reed,  c.  j. 

A Prediction  of  the  Discovery  of  Argon. 
Chem.  News,  71,  213-215. 


(1895) 


233.  Thomsen,  Julius. 


(1895) 


Ueber  die  mutmassliche  Gruppe  inaktiver  Elemente. 
Ztschr.  anorg.  Chem.,  g,  283-288. 

234.  Systematische  Gruppierung  der  chemischen  Elemente. 
Ztschr.  anorg.  Chem.,  9,  190-193. 

235.  Andrews,  W.  W. 

The  Position  of  Argon  in  the  Periodic  System. 

Chem.  News,  71,  235. 

236.  Mendeleeff,  Dmitri.  (1895) 

On  Argon. 

J.  Russ.  Chem.  Soc.,  1895,  17-20. 

237.  Crompton,  Holland.  (1895) 

Beziehung  zwischen  Valenz  und  Atomvolum- 
Ber.  d.  chem.  Ges.,  28,  148-149. 

238.  Lea,  M.  Carey.  (1895) 

Ueber  die  Beziehung  der  Farben  von  Atom,  Ion,  und 
Molekul. 

Am.  Nat.  Acad.,  April  17,  1895.  Ztschr.  anorg.  Chem., 
9,  312-328. 

239.  Seubert,  Karl.  (1895) 

Zur  Geschichte  des  periodischen  Systems. 

Ztschr.  anorg.  Chem.,  9,  334-338. 

240.  Rang,  F.  (1895) 

The  Period  Table. 

Chem.  News,  72,  200. 

241.  Pisani,  F.  (1894) 

Beziehungen  zwischen  dem  Atom — oder  Molekulargewicht 
einfacher  Korper  und  fester  Verbindungen  und  ihrer 
Dichte. 

Bull.  Soc.  Fran.  Mineral,  1894,  88-97. 

242.  Gladstone,  J.  H.  (1895) 

Specific  Refraction  and  the  Periodic  Law,  with  Reference 
to  Argon  and  other  Elements. 

Chem.  News,  72,  223-224. 

243.  Blanshard,  C.  T.  (1895) 

Specific  Volume  and  the  Genesis  of  the  Elements. 

Chem.  News,  72,  237-238. 


3°6 


INDEX  TO  LITERATURE. 


244.  Blaushard,  C.  T.  (1895) 

Boiling  Points  and  the  Genesis  of  the  Elements. 

Chem.  News,  72,  299-301. 

245.  Hill,  Edwin  A.  (1895) 

Argon— Prout’s  Hypothesis  and  the  Periodic  Law. 

Am.  J.  Sci.,  49.  4=>5-4i7- 

246.  DEELEY,  R.  M.  (.1895) 

Helium  and  Argon — Their  Places  among  the  Elements. 
Chem.  News,  72,  297-298. 

247.  Gladstone,  J.  H.  (1895) 

On  the  Place  of  Helium  in  the  Classification  of  the  Ele- 

ments. 

Chem.  News,  72,  305. 

248.  Wilde,  H.  (1895) 

On  the  Place  of  Helium  in  the  Classification  of  the  Ele- 

ments. 

Chem.  News,  72,  317. 

249.  The  same.  (1896) 

Chem.  News,  73,  35. 

250.  Meyer,  Lothar.  (1895) 

Die  Anfange  des  natiirlichen  Systems  der  chemischen  El- 
emente. 

Ostwald’s  Klassiker  der  exakten  Wissenschaften.  Leipzig. 

251.  Dennstedt,  M.  (1895) 

Ueber  das  Argon  und  seine  Stellung  im  periodischen 
System. 

Chem.  Ztg.,  19,  2164. 

252.  Preyer,  W.  (1896) 

Argon  und  Helium  im  System  der  Elemente. 

Ber.  d.  chem.  Ges.,  29,  1040-1041. 

253.  Lea,  M.  Carey.  (1896) 

On  the  Numerical  Relations  existing  between  the  Atomic 
Weights  of  the  Elements. 

Chem.  News,  73,  203. 

254.  Meyer,  Victor.  (1895) 

Probleme  der  Atomistik. 

Vortrag  gehalten  in  der  2ten  allg.  Sitzung  d.  67  Vers. 
Deutsch.  Naturf.  u.  Aerzte  zu  Lubeck.  45  pp.  Heidelberg. 

255.  Retgers,  J.  W.  (1S96) 

Ueber  die  Stellung  des  Tellurs  im  per.  System. 

Ztschr.  anorg.  Chem.,  12,  98-117. 


INDEX  TO  LITERATURE. 


307 


256.  Flavitzky,  Flavian.  (1896) 

Ueber  eine  Funktion,  welche  der  Periodizitat  der  Eigen- 
schaften  der  chemischen  Elemente  entspricht. 

Ztschr.  anorg.  Chem.,  11,  264-267. 

257.  Goldhammer,  D.  A.  (1896) 

Bemerkungen  iiber  die  analytische  Darstellung  des  period  - 
ischen  Systems  der  Elemente. 

Ztschr.  anorg.  Chem.,  12,  39-45. 

258.  Tutton,  A.  E.  (1896) 

Connection  between  the  Atomic  Weight  of  the  Contained 
Metal  and  the  Crystallographical  Characters  of  the  Iso- 
morphous  Salts.  The  Volume  and  Optical  Relation- 
ships of  the  Potassium,  Rubidium,  and  Caesium  Salts  of 
the  Monoclinic  Series  of  Double  Sulphates. 

J.  Chem.  Soc.,  69,  344-494. 

259.  Comparison  of  the  Results  of  the  Investigations  of  the  Sim- 

ple and  Double  Sulphates  containing  Potassium,  Ru- 
bidium, and  Caesium,  and  General  Deductions  therefrom 
concerning  Influences  of  the  Atomic  Weight  on  Crystal 
Characters. 

J.  Chem.  Soc.,  79.  495'5o6. 

260.  The  Bearing  of  the  Results  of  the  Investigations  of  the  Sim- 

ple and  Double  Sulphates  containing  Potassium,  Ru- 
bidium, and  Caesium,  on  the  Nature  of  the  Structural 
Unit. 

J.  Chem.  Soc.,  79.  5°7-525- 

261.  Blanshard,  C.  T.  (1895) 

Solubility  as  a Clue  to  the  Genesis  of  the  Elements. 
Chem.  News,  71,  187. 

262.  Boisbaudran,  Lecoq.  (1895) 

Remarks  on  the  Atomic  Weights. 

Chem.  News,  71,  116. 

263.  Classification  of  the  Chemical  Elements. 

Chem.  News,  71,  271-273. 

264.  DEELEY,  R.  M.  (1895) 

Argon. 

Chem.  News.  71.  75. 

265.  Atomic  Weights. 

Ibid.,  71,  244. 


3°8 


INDEX  TO  LITERATURE. 


266.  Periodic  Law. 

Ibid.,  71,  87. 

267.  Masson,  Orme.  (1896) 

Does  Hydrogen  find  its  proper  Place  at  the  Head  of  Group 
I.  or  at  the  Head  of  Group  VII.  ? 

Chem.  News,  73,  283. 


UIST  OK  AUTHORS. 


Adkins 

Ames 

Andrews  ■ • • 
Anonymous 


207 

185 


Bailey 214 

Bassett 202 

Baumhauer 82,  90 

Bayley 124 

Bazaroff  167 

Berthelot 108,  145 

Berzelius 9 

Blanshard 223,  224,  225,  226,  227,  243,  244,  261 

Blomstrand 78,  79,  90 

deBoisbaudran 262,  263 

deBoisbaudran  and  Lapparent  198 

Bornemann  (and  Gretschel) 135 

Boutlerow 120,  125 

Brauner  - 178,  190 

Brodie 66 

Biihler 187 


Carnelley 

de  Chancourtois 

Chase 

Ciamician 

Clarke 

Cooke 

Crompton 

Crookes. . f. 

Deeley 

Delauney 

Dennstedt 

Despretz 

Doebereiner 

Dulk 

Dumas 


no,  hi,  138,  139,  140,  150,  154,  195 

46 

122 

118 

123 

22,  24,  42,  43,  136,  182 


109,  156,  163,  199 

212,  216,  246,  264,  265,  266 

174,  186 

251 


5-  6,  7 

157,  158 

14,  16,  17,  27,  34,  105 


Faraday  • 
Flavitzky 
Fedaroff  • 
Fleck  ... 


20 

166,  256 

127 

....  58 


3io 


LIST  OF  AUTHORS. 


Gerber 133 

Gibbes 95 

Gibertini 1x5 

Gladstone 21,  131,  242,  247 

Gmelin 10 

Goldbammer 257 

Gretschel  (and  Bornemann) 135 

Groshans 94,  141,  144,  188 

Griinwald 165,  176,  184 

Hartley 128,  129,  153,  177 

Haughtou 175 

Hill 245 

Hinrichs 63,  64,  65,  67,  217 

v.  Huth 143 

Inquirer 52 

Kayser  and  Runge 200 

Knowles 92 

Kopp 84 

Kotikovsky 23 

Kremers  18,  19,  29,  85 

Kronberg 192 

Lapparent  (and  de  Boisbaudrau) 198 

Laurie 132 

Lea 39,  40,  4L  45.  238,  253 

Lennsen 26 

Lersch 112 

Livermore 171 

Lockyer 107 

Low 24,  25 


Mallet 

Marignac 

Masson 

Meinecke 

Mendeleeff 

73 

Mercer 

Meyer,  L 

Meyer  and  Seubert- 

Meyer,  V 

Meusel 

Mills 


1 14 

15.  37-  61,  103 

267 

4 

70.  7i,  72 

, 74.  75.  76,  98,  99.  IO°.  101,  102,  1 17,  1S1,  236 


59,  81,  91,  1 16,  148,  210,  250 

13°.  !46,  147.  1S9 

142,  254 

208 

137,  160,  161 


HIST  OF  AUTHORS. 


311 


Nasini 221 

Newlands 47.  53.  54,  55,  56,  57,  62,  86,  87,  104,  162 

Noble 51 

Noyes 197 

Odling 28,  98 

Ostwald 149,  191 


Palmer 

Patterson— Muir 

Pearson 

Pelopidas  

Penny  

Pettenkofer 

Phipson 

Pisani  

Potilizin 

Preyer  

Prout  


211 

218 

172 

134 

13 

30 

159 

241 

113 

204,  205,  206,  252 
1,  2,  3 


Ouin 


44 


Ramsay  (and  Rayleigh) 

Rang 

Rayleigh  and  Ramsay  • . 

Reed 

Remsen  

Retgers 

Reynolds 

Richter  

Roberts-Austen 

Roscoe 

Runge  ( and  Kayser ) • • • 
Rydberg 


229 

213,  240 

229 

164,  232 

....  183 


255 

155 

77 


169,  196 


93 


200 

151,  152 


Schafarik 

Schneider 

Schiitzenberger 

Sedgwick 

Seubert 

Seubert  (and  Meyer) 

Simmen 

Spring 

Stas 

Stoney  

Stransky 

Strecker 


38 

33 

126 

231 

■ 239 

130,  146,  147,  189 
97 

119 

36,  60 

173,  230 

t8o 

32 


312 


LIST  OF  AUTHORS. 


Studiosus  • • 
Sutherland  • 

Tchitcherine 
Thomsen  - • . • 
Thomson  • - • 

Traube  

Troizky 

Turner 

Tutton 


48,  49 

194 

193 

168,  219,  233,  234 

8 

215 

83 

11,  12 

220,  258,  259,  260 


Venable 179,  222 

Vogel 170 


Waechter  .. 

Wendt 

Wiik 

Wilde 

Williamson 
Wislicenus  • 


106 

201 

96 

203,  228,  248,  249 

50,  80 

209 


Zangerle 


88,  89,  121 


GENERAL  INDEX  TO  VOLUME. 


Abbe  Sped  on  Helium 

Adkins  Numerical  Relations 

Algebraic  Expression  of  Periodic  Law 

Ames  Criticism  of  Griinwald 

Argon  and  Helium  in  System 

Ascending  Series  of  Kremer’s 

Gladstone 

Atomic  Weights  of  Berzelius i8, 

Gerhardt 

Graham 

Laurent 

Cannizzaro 

Atomic  Weights  and  Densities,  Fleck 

Atomic  Weight  Differences,  Lea 

Rydberg 

Atomic  Parallels  of  Mercer 

Bassett  on  Periodic  Relations  

Baumhauer’s  Spiral  Arrangement 

Bayley’s  Arrangement 

Diagrams 158, 

Bazaroff  Numerical  Regularities 

Berthelot’s  Discussion  of  Lockyer’s  Hypothesis 

Criticism  of  Periodic  Law 

on  Primal  Matter  

Replied  to  by  Mendeldeff 

Berzelius 18,  22 

Blanshards’  Cross  Analogies 

Atomic  Heats  and  Genesis 

Boiling  Points  and  Genesis 

Melting  Points  and  Genesis 

Solubilities  and  Genesis 

Specific  Volumes 

Blomstrand 

deBoisbaudran  on  Argon,  etc 

Formation  of  Elements 

Spectroscopic  Evidence 

System 

the  Telluric  Screw 


156 
251 

240 
205 
281 
37 
39 
1 33 
33 
33 
33 
55 
69 
283 
184 
54 

245 

120 

157 
159 
213 

138 

no 

169 

229 

> 33 

279 

280 
280 
280 

279 

280 
149 

281 
278 
162 
276 

76 


3*4 


INDEX  TO  VOLUME. 


Brauner  on  Standard 

Brodie’s  Ideal  Chemistry 

New  Symbols 

Genesis  of  Elements 

Buehler  on  Nature  of  Matter 

Cannizzaro’s  Revision  of  Atomic  Weights 

Carnelley’s  Algebraic  Expression 

on  Cause  of  Periodic  Law 

on  Occurrence  of  Elements 

on  Physical  Properties 

Tables 

Cause  of  Periodic  Law,  Carnelley 

deChancourtois  Telluric  Screw 

Clarke  on  Prout’s  Hypothesis 

Classification  by  Atomicities 

Color  of  Ions 

Compound  Nature  of  Elements,  Despretz 

Dumas 

Kotikovsky 
Low 

Concentric  Ring  by  Wiik 

Constitution  of  Matter,  Brodie 

Prout  

Cooke’s  Homologous  Series 

Criticism  of  Dumas  by  Despretz 

Schafarik 

Schneider  

Criticism  of  Newland’s  Law  

Crookes’  Diagram 

Discussion  of  Lockyer’s  Hypothesis 

on  Claims  of  Newlands,  etc 

Genesis  of  Elements 

on  Prout’s  Hypothesis 

Cubiponderalgesetz 

Dalton’s  Atomic  Weights 

Atomic  Weights,  Roscoe  on 

Table  of  Atomic  Weights  

Deeley’s  Periodic  Table 

Definition  of  Atomic  Weights,  Hartley 

Griinwald 

Definition  of  Element 

Delauney’s  Numerical  Relations 

Despretz’s  Controversy  with  Dumas 


233 

70 

71 

72 
232 


55 

240 

172 

171 

166 


75;  176 
172 

•••  73 
...  154 
...  69 
...  283 


49 

49 

43 

44 
132 


70 


27 

4i 

49 

61 

60 

82 

191 

139 

84 

196 

155 

233 


14 
16 

15 
259 
224 
208 

13 

218 

49 


INDEX  TO  VOLUME.  315 

Doebereiner’s  Triads 11,  28,  29,  35 

Berzelius  on 31 

Gmelin - 31 

Double  Parallelism  of  Dumas 48 

Dumas’ Address 33 

Address,  Effect  of 35 

Controversy  with  Despretz 49 

Extension  of  Prout’s  Hypothesis 59 

Correction  of  Stas 151 

Compound  Nature  of  Elements 49 

Double  Parallelism 48 

Reviewed  by  Meyer  and  Seubert 152 

Dulk  on  Gravitation 199 

Elements  Compared  with  Compound  Radicals  by  Cooke 42 

Dumas 34 

Gladstone.  41 
Mercer- 53 
Pettenkofer  52 

Elements,  Nature  of,  Groshans 148 

Mendeleeff 148 

Meyer  148 

Equation  for  Calculating  the  Atomic  Weights,  Mills 165 

Evolution  of  the  Elements,  Wendt 243 

Explanation  of  Triads,  by  Newlands 79 

Extension  of  Prout’s  Hypothesis,  by  Dumas 59 

Faraday  on  Dumas 35 

Faraday  Lecture,  Mendeleeff 226 

Fedaroff  on  Numerical  Relations 163 

Table 164 

Flavitzky’s  Diagram 211 

Function 210,  284 

Fleck’s  Relation  between  Atomic  Weights  and  Densities  - - - 69 

Formation  of  Elements,  deBoisbaudran 278 

Function  for  Deduction  of  Properties 284 

Function  of  Thomson 275 

Genesis  of  Elements,  Crookes 196 

Genetic  System  of  Preyer 255 

Geometrical  Ratios 57 

Geometric  Illustration,  Haughton 219 

Gerber  on  Prout’s  Hypothesis 165 

Gibbes’  Diagram 130 

Synoptical  Table 126 

Gladstone’s  Ascending  Series 39 


316  index  to  volume. 

Gladstone  on  Nature  of  Elements 159 

on  Occurrence  of  Elements 171 

Gmelin’s  in  Connection  with  Prout’s  Hypothesis 23 

Extension  of  Dobereiner’s  Triads 31 

Gravitation,  Dulk  on . 199 

Groshans  on  Prout’s  Hypothesis 157 

Nature  of  Elements 148 

New  Law 166 

Group  Differences,  Dumas 48 

Lea 56,  283 

Pettenkofer 51 

Griinwald’s  Criticism  of,  by  Ames • 208 

Definition  of  Atoms 205 

Spectroscopic  Analysis 203 

Hartley’s  Criticism  of  Lockyer 161 

Definition  of  Atomic  Weights 224 

on  Spectroscopic  Evidence 161 

Haughton’s  Geometrical  Illustrations 219 

Helium,  Crookes  on 156 

in  System 281 

Hinrichs’  Classification 87 

Pantogen 86 

Spectra  of  Elements 87 

True  Atomic  Weights 264 

Homologous  Series  of  Cooke 41 

Dumas 47 

v.Huth’s  Spiral  Arrangement 168 

Ideal  Chemistry,  Brodie 70 

Inactive  Elements,  Thomsen 273 

Inception  of  the  System 282 

Isomorphism  of  Atoms 233 

Isomorphous  Salts,  Tutton 284 

Ions,  Color  of 283 

Knowles 148 

Kotikovsky 43 

Kremers’  Ascending  Series 37 

Triads 37 

Kronberg’s  Isomorphism  of  Atoms 233 

Lapparent  on  the  Telluric  Screw 76 

Laurie  on  Physical  Properties 163 

Lea  on  Atomic  Weight  Differences 2S3 

Color  of  Ions 2S3 

Geometrical  Ratios 75 


INDEX  TO  VOLUME.  317 

Lea  on  Group  Differences 56 

Numerical  Relations 59 

Physical  or  Chemical  Atoms 59 

Lennsen’s  Triads 46 

Lersch’s  Numerical  Relations 140 

Livermore’s  Classification 215 

Lockyer’s  Hypothesis 137,  161,  162,  229 

Berthelot  on 138 

Crookes’  on 139 

Logarithmic  Law,  Stoney 216 

Ludwig 148 

Marignac’s  Criticism  of  Stas - 64 

Meinecke  on  Prout’s  Hypothesis 26 

Mendeleeff  on  Argon,  etc 281 

Claim  as  a Discoverer 94 

Criticism  of  Newlands 83 

Faraday  Lecture 226 

First  Paper 91 

First  Table , 93 

Horizontal  Table 93 

Table  1871 101 

Reply  to  Berthelot 114 

Features  of  System 91,  94 

Mendeleeff  and  Meyer’s  Claims 151 

Mercer’s  Atomic  Parallels 54 

Meusel  on  the  Nature  of  the  Elements 252 

Comparison  with  Organic  Radicals 53 

Meyer’s,  Lothar,  Curve  of  Atomic  Volume 107,  108 

First  Table 85 

Ideas  as  to  Elements 148 

Inception  of  the  System 282 

Use  of  the  System  in  Teaching 264 

Claims 151 

Meyer,  Lothar,  Evolution  of  Table 96 

Table  of  1864 85,  97 

Table  of  1868 98 

Table  of  1870 100 

Later  Tables 105,  106 

Meyer  and  Seubert’s  Criticism  of  Zangerle 147 

on  Prout’s  Hypothesis 156 

Review  of  Dumas 152 

on  Standard 233 

Meyer,  Victor,  on  the  Atoms 282 

Mills’  Equation  for  the  Atomic  Weights 165 


3i8 


INDEX  TO  VOLUME. 


Modified  Arrangement  of  Venable 

v.  Monckhoven  Spectroscopic  Evidence 
deMorgan’s  Calculation  of  Probabilities 

Nasini  on  Argon,  etc 

Nature  of  Elements,  Gladstone 

Groshans  

MeuSel 

Palmer 

„ Remsen 

Nature  of  Matter,  Buehler 

Wislicenus 

Nature  of  Periodicity,  Rydberg 

Newland’s  Additional  Work 

on  Ascending  Series 

Explanation  of  Triads 

Law  of  Octaves 

Numerical  Relations 

Table  of  the  Elements 

New  Grouping  by  Thomsen 

New  Periodic  Property,  Sutherland 

New  System  of  Traube 

Nordenskiold  and  Gadolinium 

Noyes  on  Standard 

Numerical  Regularities 

Bazaroff 

Lea 

Preyer  

Waechter 

Numerical  Relations,  Delauney 

Fedaroff  ■ . . 

Adkins 

Eersch 

Stransky  

Zangerle 

Inquirer 

Newlands 

Noble  

Studiosus  


269,  270 
• • • 162 
• • • • 40 

281 

....  159 

148 

• • • 252 

261 

225 

232 

....  258 
....  181 
....  123 
....  77 

....  79 

....  78 

....  77 

80 

272 

....  239 

267 

198 

••••  233 
....  119 

213 

....  58 

....  258 
••••  135 
....  218 
....  163 
....  251 

140 

....  225 


65.  77 
..  65 

..  65 


Occurrence  of  Elements 171 

Odling’s  Triads 52 

Organic  Radicals,  Pelopidas 167 

Origin  of  Elements,  by  Wilde 248 

Ostwald’s  Criticism  of  Mendel£eff 115 

on  Standard 233 


INDEX  TO  VOLUME.  319 

Pairing  of  the  Elements 67 

Palmer  on  the  Nature  of  the  Elements 261 

Patterson-Muir 13 

Parallelism  of  the  Elements 66 

Pearson’s  Atomic  Hypothesis 216 

Pelopidas  Comparison  with  Organic  Radicals 167 

Reviewed  by  Mendeleeff  • . 230 

Periodic  Arrangement  of  Rang 266 

Periodic  Law,  Announcement  of 91 

Forerunners  63 

Criticized  by  Berthelot no 

not  Recognized 107 

Reception  of 95 

Periodic  Relations  of  Bassett 245 

Periodic  Table  of  Deeley 260 

Pettenkofer’s  Group  Differences 51 

Phipson’s  New  Atomic  Theory 200 

Phlogiston  of  Phipson 200 

Physical  or  Chemical  Atoms 59 

Predictions  by  Mendeldeff 231 

Preyer’s  Genetic  System 255 

Numerical  Regularities 238 

Primal  Element  of  Simmeu 135 

Zangerle 142 

Primal  Matter,  Berthelot 169 

Perissad  Law 215 

Prefatory  Sketch 1 

Problems  of  the  Atoms 282 

Prout’s  First  Article 20 

Second  Article 21 

Later  Views 25,  27 

Prout’s  Hypothesis n,  20 

Berzelius  on 22 

Clarke 154 

Crookes 155 

Dumas 24 

Gmelin 23 

Gerber 163 

Groshans 157 

Hoffman 23 

Meyer  and  Seubert 156 

Victor  Meyer 151 

Mallet 151,  152 

Penny 24 

Turner 23 


320  INDEX  TO  VOLUME. 

Prout’s  Hypothesis,  Wilde  on 249 

Extension  of--  25,  59 

Revival  of 15 1 

Opposed  by  Stas 63 

Rang  on  Argon 281 

Periodic  Arrangement 266 

Rational  Atomic  Weights,  Thomsen 271 

Reed  on  Argon 281 

Valence  and  Atomic  Weights 201 

Remsen  on  Nature  of  the  Elements 225 

Reynold’s  Diagram 185,  187 

Revision  of  Atomic  Weights 24 

Berzelius 18 

Stas 63 

Turner 23 

Richter’s  Equivalents 28 

Roscoe  on  Atomic  Weights  of  Dalton 16 

Rydberg  on  Nature  of  Periodicity 181 

Atomic  Weight  Differences 184 

Table 183 

Spectroscopic  Analysis,  Griinwald 203 

Spectroscopic  Evidence,  deBoisbaudran 162 

Gladstone 160 

Hartley 161 

Hinrichs 82 

Lockyer 137 

Vogel 162 

vonMonckhoven 162 

Spiral  Arrangement  of  Baumhauer 120 

v.  Huth 168 

Spring’s  Diagram  of  the  Elements 177,  178 

Sedgwick  on  Argon 281 

Siinmen’s  Primal  Element 135 

Standard,  Controversy  over 233 

Stas  Corrected  by  Dumas 15 1 

Opposition  to  Prout’s  Hypothesis 63 

Revision  of  Atomic  Weights 63 

Stoney’s  Logarithmic  Law  of  Atomic  Weights 216 

Stransky’s  Numerical  Relations 225 

Sutherland’s  New  Periodic  Property 239 

Synoptical  Table  of  Gibbes 126 

System  of  deBoisbaudran 276 


INDEX  TO  VOLUME.  32 1 

Table  of  Atomic  Weights,  Berzelius 18 

Dalton 15 

Thomson 17 

Wollaston 17 

Tchitcherine’s  System  of  Elements 235 

Telluric  Screw 73 

Thomson 17,  22 

Thomsen’s  Function 275 

Inactive  Elements 273 

New  Grouping 272 

Rational  Atomic  Weights 271 

on  Unity  of  Matter 209 

Traube’s  New  System 267 

Triads,  Dobereiner’s 11,  28,  29,  35 

Lennseu 46 

Odling  52 

Developments  of 33 

True  Atomic  Weights 264 

Tutton  on  Isomorphous  Salts 284 

Unity  of  Matter 12,  120,  209 

Thomsen 209 

Use  of  the  System  in  Teaching 264 

Valence  and  Atomic  Weight 201 

Venable,  Modified  Arrangement 269 

on  Standard 233 

Vogel  on  Spectroscopic  Evidence 162 

Wachter’s  Numerical  Regularities 135 

Welsbach  and  Didymium 199 

Wendt,  Evolution  of  Elements 243 

Wiik’s  Arrangement 132 

Wilde  on  Origin  of  Elements 248 

Prout’s  Hypothesis 249 

Williamson’s  Atomic  Weights 69 

Classification 69 

Wislicenus  on  Nature  of  Matter 258 

Wollaston 17 

Zangerle  Critized  by  Meyer  and  Seubert 147 

Numerical  Relations 139 

Primal  Elements 142 

Table  of  Elements 144 


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